Oil tank ventilation system and ship

Abstract

The invention belongs to the technical field of ships, and discloses an oil tank ventilation system and a ship. The oil tank ventilation system comprises first ventilation branch pipes, a first ventilation main pipe, an overflow box and a second ventilation main pipe, all the oil tanks are connected with the first ventilation branch pipes, and the first ventilation branch pipes of all the oil tanks are arranged in parallel and connected with the first ventilation main pipe. The first ventilation main pipe is connected with the overflow box through the discharge pipe, the installation position of the overflow box is lower than that of the first ventilation main pipe, the overflow box is connected with the second ventilation main pipe, the upper end of the second ventilation main pipe extends to the position above the ship main deck, and the ventilation cap is arranged at the upper end of the second ventilation main pipe. Design efficiency is improved, interference risks are reduced, materials such as pipes and ventilation caps are effectively saved, and effectiveness and safety of a ventilation system are improved.

Description

Technical Field

[0001] The present application relates to the field of ship technology, and in particular to an oil tank ventilation system and a ship. Background Art

[0002] To facilitate the injection and discharge of oil from various oil tanks on a ship, each tank needs to be equipped with a vent pipe, the upper end of which needs to extend above the main deck. Each vent pipe also needs to be equipped with a separate vent cap to prevent foreign matter from entering the pipe. However, due to the large number of oil tanks on a ship, their wide distribution area, and the large diameter of the vent pipes, the design phase of the oil tank ventilation scheme requires not only comprehensive consideration of the layout of the vent pipes, but also planning the path of the vent pipes to avoid interference between them. This undoubtedly increases the difficulty of designing the oil tank ventilation scheme given the limited space resources on board. Furthermore, designing a separate vent cap for each vent pipe not only increases the assembly workload but also increases material costs.

[0003] To address the aforementioned issues, a related art provides an oil tank venting system comprising vent branches, a manifold, and a main vent pipe. Each oil tank is connected to a vent branch, which converges into a manifold. The main vent pipe is then connected to the manifold, and finally, venting is achieved through the vent cap of the main vent pipe. This oil tank venting system can optimize the layout of the vent pipes and reduce the number of vent caps.

[0004] However, this oil tank venting system has the following problems: the venting pipe is tilted, with the lower end connected to the waste oil drain pipe and the higher end connected to the main vent pipe, while the vent branches are connected to the middle of the venting pipe. This design makes it more difficult for gas in the vent branches near the waste oil drain pipe to be discharged compared to gas in the vent branches near the main vent pipe. In extreme cases, when the amount of gas in a vent branch near the main vent pipe is large, the pressure in the venting pipe at the connection with the vent branch pipe will increase, preventing gas in other vent branches farther away from the main vent pipe from flowing smoothly to the main vent pipe, or even preventing it from flowing effectively into the venting pipe. This results in poor venting or even venting failure, which in turn affects the filling and discharge of oil from the oil tank.

[0005] This section provides background information related to the present application which is not necessarily prior art. Summary of the Invention

[0006] The present application aims to solve or at least alleviate some or all of the above-mentioned problems. To this end, the present application aims to provide an oil tank venting system and vessel that can reduce the difficulty of piping layout, improve design efficiency, reduce interference risks, effectively save materials such as pipes and vent caps, and enhance the effectiveness and safety of the venting system.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, the present application provides an oil tank venting system for a ship having multiple oil tanks, the oil tank venting system comprising:

[0009] a first ventilation branch pipe, each of the oil tanks is connected to the first ventilation branch pipe, and the first ventilation branch pipes of the oil tanks are arranged in parallel;

[0010] a first ventilation main pipe connected to the first ventilation branch pipe of each oil tank;

[0011] an overflow box connected to the first ventilation main pipe through a discharge pipe, and the installation position of the overflow box is lower than the installation position of the first ventilation main pipe;

[0012] The lower end of the second ventilation main pipe is connected to the overflow box, and the upper end of the second ventilation main pipe extends above the main deck of the ship, and a ventilation cap is provided at the upper end of the second ventilation main pipe.

[0013] As an optional solution for the oil tank ventilation system, the oil tank ventilation system also includes an overflow tank and a second ventilation branch pipe, the overflow tank is connected to the overflow box through an overflow pipe, and the overflow tank is connected to the second ventilation main pipe through the second ventilation branch pipe.

[0014] As an optional solution of the oil tank ventilation system, the diameter of the second ventilation branch pipe is larger than the diameter of the first ventilation branch pipe; and / or

[0015] The diameter of the first ventilation main pipe is larger than the diameter of the first ventilation branch pipe; and / or

[0016] The diameter of the second ventilation main pipe is larger than the diameter of the first ventilation branch pipe.

[0017] As an optional solution for the oil tank ventilation system, a liquid level detector is provided in the overflow tank.

[0018] As an optional solution for the oil tank ventilation system, the upper end of each of the first ventilation branch pipes has a gooseneck bend, and the gooseneck bend is connected to the first ventilation main pipe and is located above the first ventilation main pipe.

[0019] As an optional solution for the oil tank ventilation system, the discharge pipe is connected to the bottom of the pipe section corresponding to the maximum diameter of the first ventilation main pipe.

[0020] As an optional solution of the oil tank ventilation system, when the length and width of the oil tank are both greater than or equal to 7 meters, the oil tank is connected to at least two of the first ventilation branches;

[0021] When the length and width of the oil tank are both less than 7 meters, the oil tank is connected to one of the first vent branches.

[0022] As an optional solution for the oil tank ventilation system, each oil tank is connected to an injection branch pipe, and the ratio between the total cross-sectional area of ​​all first ventilation branches connected to each oil tank and the cross-sectional area of ​​the injection branch pipe connected thereto is not less than 1.25.

[0023] As an optional solution for the oil tank ventilation system, the injection branch pipes of each oil tank are connected to the injection delivery system through an injection main pipe, and the ratio between the cross-sectional area of ​​the first ventilation main pipe at the maximum diameter and the cross-sectional area of ​​the injection main pipe is not less than 1.25.

[0024] In a second aspect, the present application provides a ship, comprising a hull and an oil tank venting system as described in any one of the above items, wherein the oil tank venting system is arranged on the hull.

[0025] The beneficial effects of this application are:

[0026] The oil tank ventilation system provided by the present application is such that the gas in each oil tank enters the first ventilation main pipe through each first ventilation branch pipe, then enters the overflow box and is discharged through the second ventilation main pipe. This arrangement not only allows the oil in the first ventilation main pipe to enter the overflow box, avoiding the oil from clogging the connecting parts of the first ventilation main pipe and each first ventilation branch pipe, but also avoids local air pressure instability in the first ventilation main pipe, ensuring that the gas in all first ventilation branch pipes can smoothly enter the overflow box and be discharged through the second ventilation main pipe, which can reduce the difficulty of pipeline layout, improve design efficiency, reduce interference risks, effectively save materials such as pipes and ventilation caps, and improve the effectiveness and safety of the ventilation system.

[0027] The ship provided in this application, by applying the above-mentioned oil tank ventilation system, can reduce the difficulty of pipeline layout, reduce the risk of interference, effectively save materials such as pipes and ventilation caps, and improve the effectiveness and safety of the ventilation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present application and these drawings without any creative work.

[0029] Figure 1 It is a structural schematic diagram of the oil tank ventilation system provided in an embodiment of the present application.

[0030] Figure 2 yes Figure 1A partial enlarged view of the connection between the first ventilation branch pipe and the first ventilation main pipe.

[0031] Reference numerals:

[0032] 100, oil tank; 101, fuel storage tank; 102, main engine fuel daily service tank; 103, auxiliary engine fuel daily service tank; 200, drain tank; 300, overflow tank; 400, main deck; 500, engine room platform deck; 600, double bottom; 700, chimney top;

[0033] 11. First ventilation branch pipe; 111. Gooseneck bend; 12. First ventilation main pipe; 13. Second ventilation main pipe; 14. Second ventilation branch pipe; 15. Third ventilation branch pipe;

[0034] 21. Injection branch pipe; 22. Injection main pipe;

[0035] 3. Breathable cap;

[0036] 41. Overflow box; 42. Discharge pipe; 43. Overflow pipe; 44. Liquid level detector. DETAILED DESCRIPTION

[0037] Before any embodiments of the present application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the foregoing drawings.

[0038] In this application, the terms "comprises," "includes," "has," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0039] In this application, the term "and / or" describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this application generally indicates that the related objects are in an "and / or" relationship.

[0040] In this application, the terms "connect," "combine," "couple," and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without an intermediary, and an indirect connection refers to two parts or components being connected to at least one intermediary, with the two parts or components being connected via the intermediary. Furthermore, "connect" and "couple" are not limited to physical or mechanical connections or couplings and may include electrical connections or couplings.

[0041] In this application, it will be understood by those skilled in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerance caused by manufacturing, assembly, use, etc. associated with a specific value. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0042] In this application, it will be understood by those skilled in the art that the function performed by an assembly can be performed by one assembly, multiple assemblies, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one assembly, or a combination of multiple parts.

[0043] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to the other element "upper" or "lower", but also be indirectly connected to the other element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, below can include directly below, lower left, lower right, lower front and lower back, etc.

[0044] like Figure 1As shown, the present application provides a ship, including a hull and an oil tank ventilation system. The hull has multiple oil tanks 100. The oil tank ventilation system is arranged on the hull and connected to the oil tanks 100 to facilitate the injection and discharge of oil in the oil tanks 100.

[0045] exist Figure 1 In the embodiment, the multiple oil tanks 100 include fuel storage tanks, main engine fuel daily tanks 102, and auxiliary engine fuel daily tanks 103. There are six fuel storage tanks, all of which are located in the double bottom 600 of the hull. There are two main engine fuel daily tanks 102, and two auxiliary engine fuel daily tanks 103. Both the main engine fuel daily tanks 102 and the auxiliary engine fuel daily tanks 103 are located on the engine room platform deck 500. Of course, in other embodiments, for different ships, the classification of the oil tanks 100 is not limited to the above three categories, and the number of oil tanks 100 is not limited to the above number.

[0046] It should be noted that when the oil tank 100 is used to describe this application, it means that the design schemes of all oil tanks 100 adopt this description. When the fuel storage tank is used for description, it only means that the design scheme of the fuel storage tank adopts this description. Similarly, when the main engine fuel daily tank 102 or the auxiliary engine fuel daily tank 103 is used for description, it only means that the design scheme of the main engine fuel daily tank 102 or the auxiliary engine fuel daily tank 103 adopts this description.

[0047] To facilitate the injection of oil into the oil tanks 100, the vessel also includes an injection and delivery system, an injection manifold 22, and injection branches 21. Each oil tank 100 is connected to an injection branch 21, which is connected to the injection and delivery system via the injection manifold 22. When oil needs to be replenished in the oil tanks 100, the corresponding oil tank 100 can be refueled through the injection and delivery system, the injection manifold 22, and each injection branch 21. It will be appreciated that valves are installed at the connection between the injection branch 21 and each oil tank 100. These valves can be electrically controlled to remotely open or close the corresponding valve as needed.

[0048] After oil is injected into each oil tank 100 via the injection and delivery system, a certain amount of oil will remain in the injection manifold 22. To prevent the oil in the injection manifold 22 from being wasted or accumulated for a long time, the vessel also includes a discharge tank 200. The discharge tank 200 is connected to the injection manifold 22 via a pipeline to collect the oil injected into the manifold 22 after oil injection. The discharge tank 200 is connected to the first vent manifold 12 via a third vent branch pipe 15 to regulate the air pressure balance within the discharge tank 200.

[0049] It is worth noting that the main engine fuel daily tank 102 and the auxiliary engine fuel daily tank 103 are not only connected to the injection and delivery system through the injection branch pipe 21 and the injection main pipe 22, but are also connected to each fuel storage tank and the discharge tank 200 through other pipelines, thereby realizing the oil replenishment operation of two paths ( Figure 1 The connecting pipelines between the main engine fuel daily tank 102 and the auxiliary engine fuel daily tank 103 and each fuel storage tank are not shown).

[0050] Continue to see Figures 1 to 2 As shown, the oil tank ventilation system provided in the present application includes a first ventilation branch pipe 11, a first ventilation main pipe 12, an overflow box 41 and a second ventilation main pipe 13. Each oil tank 100 is connected to the first ventilation branch pipe 11, and the first ventilation branch pipe 11 of each oil tank 100 is arranged in parallel and connected to the first ventilation main pipe 12; the first ventilation main pipe 12 is connected to the overflow box 41 through a discharge pipe 42, and the installation position of the overflow box 41 is lower than the installation position of the first ventilation main pipe 12, and the overflow box 41 is connected to the second ventilation main pipe 13, the upper end of the second ventilation main pipe 13 extends above the main deck 400 of the ship, and the upper end of the second ventilation main pipe 13 is provided with a ventilation cap 3. In other words, the gas in each oil tank 100 enters the first ventilation main pipe 12 through each first ventilation branch pipe 11, then enters the overflow tank 41 and is discharged through the second ventilation main pipe 13. This arrangement not only allows the oil in the first ventilation main pipe 12 to enter the overflow tank 41, preventing oil from clogging the connection between the first ventilation main pipe 12 and each first ventilation branch pipe 11, but also prevents local air pressure instability in the first ventilation main pipe 12, ensuring that the gas in all first ventilation branch pipes 11 can smoothly enter the overflow tank 41 and be discharged through the second ventilation main pipe 13. The ventilation cap 3 is a ventilation structure with a fireproof net.

[0051] The first ventilation manifold 12 is mounted on the main deck 400, as is the overflow tank 41. However, the overflow tank 41 is mounted lower than the first ventilation manifold 12 to allow the oil in the first ventilation manifold 12 to flow into the overflow tank 41 under the action of gravity. Furthermore, the first ventilation manifold 12 is located at the chimney trunk on the main deck 400, and the upper end of the second ventilation manifold 13 extends above the chimney top 700 to minimize the impact of exhaust from the second ventilation manifold 13 on ship crew and passengers.

[0052] To ensure that the oil in the first ventilation manifold 12 can flow smoothly into the overflow tank 41, a drain pipe 42 is connected to the bottom of the pipe section corresponding to the largest diameter of the first ventilation manifold 12. This allows the oil in the first ventilation manifold 12 to preferentially converge at the pipe section corresponding to the largest diameter, and then flow into the overflow tank 41 through the drain pipe 42.

[0053] A liquid level detector 44 is installed in the overflow tank 41. This detector is used to monitor the oil level in the overflow tank 41 in real time and provide feedback to the operator to prevent excessive oil from affecting ventilation. For example, a float level switch can be used as the liquid level detector 44. Initially, an alarm level value is set in the control system. When the oil in the overflow tank 41 reaches the alarm level, the control system issues an alarm, prompting the operator to take appropriate action.

[0054] To fully utilize the oil in the overflow tank 41, the oil tank venting system also includes an overflow tank 300 and a second vent branch pipe 14. The overflow tank 300 is connected to the overflow tank 41 via an overflow pipe 43, which in turn is connected to the second vent main pipe 13 via the second vent branch pipe 14. This arrangement allows the oil in the overflow tank 41 to flow into the overflow tank 300 through the overflow pipe 43, while the gas in the overflow tank 300 can enter the second vent main pipe 13 via the second vent branch pipe 14 and finally be discharged from the second vent main pipe 13. Furthermore, the main engine fuel daily service tank 102 and the auxiliary engine fuel daily service tank 103 are also connected to the overflow tank 300 via pipelines, fully utilizing the oil in the overflow tank 300.

[0055] Furthermore, the outlet of the overflow pipe 43 in the overflow box 41 should be higher than the height of the detection end of the liquid level detector 44 to ensure that the oil in the box first triggers the liquid level switch and then overflows from the overflow pipe 43 into the overflow chamber 300.

[0056] The diameter of the first main ventilation pipe 12 is larger than that of the first branch ventilation pipe 11, ensuring pressure balance within the pipeline and ensuring that gas in the first branch ventilation pipe 11 can flow smoothly into the first main ventilation pipe 12. The diameter of the second main ventilation pipe 13 is larger than that of the first branch ventilation pipe 11, allowing gas in the overflow tank 41 to be discharged from the second main ventilation pipe 13 more easily and preventing it from flowing back into the first main ventilation pipe 12. The diameter of the second branch ventilation pipe 14 is larger than that of the first branch ventilation pipe 11, ensuring that gas in the overflow chamber 300 can quickly pass through the second branch ventilation pipe 14 and enter the second main ventilation pipe 13, thereby regulating the pressure within the overflow chamber 300. In this embodiment, the diameters of the second branch ventilation pipe 14, the first branch ventilation pipe 12, and the second branch ventilation pipe 13 are the same and all larger than the first branch ventilation pipe 11.

[0057] During design, the diameters of the first ventilation branch pipes 11, second ventilation branch pipes 14, first ventilation manifold 12, and second ventilation manifold 13 must be designed with reference to the diameters of the injection branch pipes 21 and injection manifold 22. The design principles are: the ratio of the total cross-sectional area of ​​all first ventilation branch pipes 11 connected to each oil tank 100 to the cross-sectional area of ​​the injection branch pipes 21 to which they are connected must be no less than 1.25; and the ratio of the cross-sectional area of ​​the first ventilation manifold 12 at its maximum diameter to the cross-sectional area of ​​the injection manifold 22 must be no less than 1.25. Furthermore, when the length and width of an oil tank 100 are both greater than or equal to 7 meters, at least two first ventilation branch pipes 11 are connected to the tank 100; when the length and width of an oil tank 100 are both less than 7 meters, only one first ventilation branch pipe 11 is connected to the tank 100.

[0058] In this embodiment, the length and width of each fuel storage tank are both greater than or equal to 7 meters. Each fuel storage tank is connected to the first ventilation manifold 12 via two first ventilation branch pipes 11. The diameter of the injection branch pipe 21 connected to each fuel storage tank is 150 mm, and the diameter of the two first ventilation branch pipes 11 connected to it is both 125 mm. Of course, the diameter of the first ventilation branch pipes 11 connected to each fuel storage tank can also be 120 mm, 130 mm, 135 mm, 140 mm, etc., as long as the ratio between the total cross-sectional area of ​​all first ventilation branch pipes 11 connected to each fuel storage tank and the cross-sectional area of ​​the injection branch pipe 21 connected to each fuel storage tank is not less than 1.25. Examples are not provided here.

[0059] In this embodiment, the length and width of the main engine fuel tank 102 and the auxiliary engine fuel tank 103 are both less than 7 meters. Each of these tanks is connected to the first ventilation manifold 12 via a first ventilation branch pipe 11. The injection branch pipe 21 connecting each main engine fuel tank 102 and auxiliary engine fuel tank 103 has a diameter of 40 mm, and the diameter of each first ventilation branch pipe 11 is 65 mm. As long as the ratio of the total cross-sectional area of ​​the first ventilation branch pipes 11 connecting the main engine fuel tank 102 and auxiliary engine fuel tank 103 to the cross-sectional area of ​​the injection branch pipe 21 connected thereto is no less than 1.25, this will not be further illustrated here.

[0060] It should be noted that the design of the vent pipes for the discharge tank 200 and overflow tank 300 can refer to the vent pipe design for the oil tank 100. Specifically, when the length and width of the discharge tank 200 and overflow tank 300 are both less than 7 meters, each tank 200 and overflow tank 300 is connected to a vent pipe. For example, the overflow tank 300 is connected to the second main vent pipe 13 via a second vent branch pipe 14 with a maximum diameter of 200 mm. The discharge tank 200 is connected to the first main vent pipe 12 via a third vent branch pipe 15 with a maximum diameter of 125 mm. Furthermore, the first main vent pipe 12 is composed of multiple pipes spliced ​​together, with a maximum diameter of 200 mm, and the diameter of the second main vent pipe 13 is 200 mm.

[0061] Figure 2 for Figure 1 A partial enlarged view of the connection between the first ventilation branch pipe 11 and the first ventilation main pipe 12. Figure 2 As shown, the upper end of each first ventilation branch pipe 11 has a gooseneck bend 111, which is connected to the first ventilation main pipe 12 and is located above the first ventilation main pipe 12. It can not only ensure that the oil in the first ventilation branch pipe 11 can flow into the first ventilation main pipe 12, but also prevent the oil in the first ventilation main pipe 12 from flowing back into the first ventilation branch pipe 11, affecting the gas in the first ventilation branch pipe 11 from entering the first ventilation main pipe 12.

[0062] In summary, the oil tank venting system provided by this application can reduce the difficulty of piping layout, improve design efficiency, reduce interference risks, effectively save materials such as pipes and vent caps 3, and improve the effectiveness and safety of the venting system. The details are as follows:

[0063] 1) Each oil tank 100 discharges gas into the first vent main pipe 12 through the first vent branch pipe 11. The gas and oil in the first vent main pipe 12 first enter the overflow box 41. Then, after oil-liquid separation, the gas is discharged from the second vent main pipe 13. This design does not require the vent pipes of each oil tank 100 to extend to the upper deck and be equipped with separate vent caps 3. The vent cap 3 only needs to be provided at the upper end of the second vent main pipe 13. This reduces the difficulty of pipeline layout, improves design efficiency, reduces interference risks, and saves pipes and the number of vent caps 3.

[0064] 2) The gas and oil in the first ventilation main pipe 12 first enter the overflow box 41. A liquid level detector 44 is provided in the overflow box 41 to realize a liquid level alarm function, thereby preventing excessive oil from escaping from the ventilation cap 3 and improving the safety of the ventilation system.

[0065] 3) The oil in the overflow box 41 can flow into the overflow chamber 300, which can further prevent excessive oil in the overflow box 41 from escaping from the vent cap 3. Combined with the liquid level alarm function of the overflow box 41, the safety of the vent system can be further improved.

[0066] 4) The upper end of the second ventilation main pipe 13 extends above the chimney top 700, and the gas discharged from the second ventilation main pipe 13 is far away from the main deck 400 area, which can reduce the impact of the gas discharged from the second ventilation main pipe 13 on staff and passengers.

[0067] The above shows and describes the basic principles, main features and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of this application.

Claims

1. An oil tank venting system for a ship having a plurality of oil tanks (100), characterized in that: The oil tank ventilation system includes: A first ventilation branch pipe (11), each of the oil tanks (100) is connected to the first ventilation branch pipe (11), and the first ventilation branch pipes (11) of each of the oil tanks (100) are arranged in parallel; A first ventilation main pipe (12) connected to the first ventilation branch pipe (11) of each oil tank (100); An overflow box (41) is connected to the first ventilation main pipe (12) through a discharge pipe (42), and the installation position of the overflow box (41) is lower than the installation position of the first ventilation main pipe (12); The second ventilation main pipe (13) has its lower end connected to the overflow box (41) and its upper end extends above the main deck (400) of the ship, and a ventilation cap (3) is provided at the upper end of the second ventilation main pipe (13).

2. The oil tank venting system according to claim 1, characterized in that: The oil tank ventilation system further comprises an overflow tank (300) and a second ventilation branch pipe (14); the overflow tank (300) is connected to the overflow box (41) via an overflow pipe (43), and the overflow tank (300) is connected to the second ventilation main pipe (13) via the second ventilation branch pipe (14).

3. The oil tank venting system according to claim 2, characterized in that: The diameter of the second ventilation branch pipe (14) is greater than the diameter of the first ventilation branch pipe (11); and / or The diameter of the first ventilation main pipe (12) is greater than the diameter of the first ventilation branch pipe (11); and / or The diameter of the second ventilation main pipe (13) is greater than the diameter of the first ventilation branch pipe (11).

4. The oil tank venting system according to claim 1, characterized in that: A liquid level detector (44) is provided in the overflow box (41).

5. The oil tank venting system according to claim 1, characterized in that: The upper end of each of the first ventilation branch pipes (11) has a gooseneck bend (111), and the gooseneck bend (111) is connected to the first ventilation main pipe (12) and is located above the first ventilation main pipe (12).

6. The oil tank venting system according to claim 1, characterized in that: The discharge pipe (42) is connected to the bottom of the pipe section corresponding to the maximum diameter of the first ventilation main pipe (12).

7. The oil tank venting system according to any one of claims 1 to 6, characterized in that: When the length and width of the oil tank (100) are both greater than or equal to 7 meters, the oil tank (100) is connected to at least two of the first ventilation branches (11); When the length and width of the oil tank (100) are both less than 7 meters, the oil tank (100) is connected to a first vent branch pipe (11).

8. The oil tank venting system according to claim 7, characterized in that: Each of the oil tanks (100) is connected to an injection branch pipe (21), and the ratio between the total cross-sectional area of ​​all the first vent branches (11) connected to each of the oil tanks (100) and the cross-sectional area of ​​the injection branch pipe (21) connected thereto is not less than 1.

25.

9. The oil tank venting system according to claim 7, characterized in that: The injection branch pipe (21) of each oil tank (100) is connected to the injection delivery system via the injection main pipe (22), and the ratio between the cross-sectional area of ​​the maximum diameter of the first vent main pipe (12) and the cross-sectional area of ​​the injection main pipe (22) is not less than 1.

25.

10. A ship, characterized in that: The oil tank venting system comprises a hull and an oil tank venting system according to any one of claims 1 to 9, wherein the oil tank venting system is arranged on the hull.

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