LNG ship fuel tank swash bulkhead structure

Abstract

The utility model discloses a swash bulkhead structure of an LNG ship fuel tank, and belongs to the technical field of fluid swash in ship engineering. The swash bulkhead structure comprises a liquid container wall, a perimeter structure and a curved bulkhead, and the perimeter structure is perpendicular to the liquid container wall and fixedly connected with the liquid container wall; the curved bulkhead is fixedly connected with the perimeter structure; the curved bulkhead is provided with a plurality of through holes serving as liquid flowing channels. Compared with a plane swash bulkhead, the swash bulkhead can effectively disperse pressure, has better structural strength and reduces stress concentration due to the curved surface shape, so that the risk of cracking or failure is reduced, and the swash bulkhead has better safety. And as the internal stress of the curved surface structure is uniformly distributed, fatigue damage is not easy to occur, and the curved surface structure has better deformation resistance under long-term load. Under the condition of the same strength, the curved surface structure can be suitable for fewer materials, and the construction cost and weight are reduced. The whole scheme has the characteristics of high safety and low construction cost.

Description

Technical Field

[0001] This utility model relates to a bulkhead structure for LNG ship fuel tank oscillation, which belongs to the technical field of fluid oscillation in marine engineering. Background Technology

[0002] The structural design of sway-damping bulkheads must meet the requirements of international codes and standards. These codes and standards specify the selection and calculation methods for sway loads, as well as the required structural strength standards. Traditional sway-damping bulkheads inside LNG liquid fuel tanks are planar. Planar structures have low load transfer efficiency, generate large bending moments within the structure, and are prone to stress concentration at support points and connections. Furthermore, planar structures rely primarily on the bending strength of the material, failing to fully utilize its compressive strength. To ensure sufficient structural strength, more material is required, necessitating thicker plates and higher-specification strips, increasing cost and weight. Additionally, sway-damping bulkheads must resist sway loads, the amplitude of which varies periodically with the liquid movement; violent swaying can also generate significant impact loads. Under long-term repeated loading, planar bulkhead structures are prone to fatigue failure and significant deformation, affecting their functionality. Utility Model Content

[0003] To address the aforementioned problems, this utility model provides a bulkhead structure for LNG ship fuel tanks that reduces the bulkhead thickness and lowers manufacturing costs while maintaining structural strength. A specific form of bulkhead structure for LNG ship fuel tanks is proposed.

[0004] The technical solution adopted by this utility model is: a LNG ship fuel tank bulkhead structure, in which the curved bulkhead is connected to the liquid container wall through a perimeter structure, the transverse and longitudinal strips on the curved bulkhead form a grid structure, and the curved bulkhead has through holes evenly distributed as liquid channels.

[0005] Furthermore, the webs of the transverse and longitudinal strips are perpendicular to the curved bulkhead.

[0006] Furthermore, the perimeter structure is a ring-shaped plate, and the plate surface of the perimeter structure is perpendicular to and fixedly connected to the wall of the liquid container.

[0007] Furthermore, the through hole is a circular hole or a fan-shaped hole.

[0008] Furthermore, the total area of ​​the through holes accounts for 30-40%.

[0009] Furthermore, the curved bulkhead has a radius of curvature of 10,000-15,000 mm, a curvature height of approximately 800-1,200 mm, and a bulkhead thickness of 8-15 mm.

[0010] The beneficial effects of this utility model are as follows: The problem to be solved by this utility model is to provide a new type of LNG ship fuel tank bulkhead structure that meets the requirements of international norms and standards in terms of strength, safety, deformation resistance and light weight.

[0011] This invention, based on in-depth analysis using ship structural mechanics theory, transforms the planar structure of the sway-damping bulkhead into a curved structure. This allows for more efficient material utilization, resulting in higher structural strength, greater durability, and reduced susceptibility to damage and significant deformation. While meeting international guidelines and standards, it also reduces bulkhead plate thickness and component specifications, leading to lighter weight and lower material and processing costs. Attached Figure Description

[0012] Figure 1 This is a front view of the curved sway-damping bulkhead.

[0013] Figure 2 This is a side view of the curved sway-damping bulkhead.

[0014] Figure 3 The results are finite element analysis of the curved sway control bulkhead (10mm thick), with stress measured in Pa.

[0015] Figure 4 The results are finite element analysis of the planar oscillation bulkhead (14mm thick), with stress in Pa.

[0016] In the diagram: 1. Perimeter structure, 2. Curved bulkhead, 3. Liquid container wall, 4. Transverse strip, 5. Longitudinal strip, 6. Through hole. Detailed Implementation

[0017] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention, but are not limited thereto, unless otherwise stated.

[0018] Based on international standards and specifications, the calculation conditions for the sloshing bulkhead were determined. The sloshing bulkhead primarily bears the sloshing load of the liquid inside the tank. Sloshing loads are periodic, long-term loads that may cause fatigue failure of the structure, and they may also cause significant impact on the bulkhead.

[0019] In response to this stress state, and in accordance with ship structural mechanics theory, a curved sway-damping bulkhead was designed to make full use of the material's compressive strength, enabling it to better resist sway loads, improve the strength of the sway-damping bulkhead, and reduce the required plate thickness and strip specifications.

[0020] Meanwhile, to verify the reliability of the structure, strength analysis was conducted using numerical simulation. The numerical analysis results demonstrate that, compared to planar bulkheads, curved sway-damping bulkheads can effectively resist sway loads and meet international specifications and standards.

[0021] The specific embodiments of this utility model are described in detail below with reference to the technical solution:

[0022] Example 1

[0023] like Figure 1 As shown, the liquefied natural gas storage tank wall of this embodiment includes: a liquid container wall 3 and a perimeter structure 1, the perimeter structure 1 being fixedly connected to the liquid container wall 3; a curved wall 2, the curved wall 2 being fixedly connected to the perimeter structure 1; the curved wall 2 having a plurality of through holes 6 as channels for liquid flow. The through holes 6 are circular holes and fan-shaped holes.

[0024] In this embodiment, the liquid container is selected as a liquid tank, or liquid vessel. The material of the sloshing chamber wall is selected to be the same as the steel of the liquid container shell or other metal materials, such as low-temperature resistant austenitic steel, nickel steel, stainless steel or other low-temperature resistant metal materials.

[0025] The perimeter structure 1 is a ring-shaped plate, with its surface perpendicular to the liquid container wall 3 and fixedly connected. The curved bulkhead 2 is fixedly connected to the perimeter structure 1, and together they form the sway-controlling bulkhead. The perimeter structure 1 is the end face of the sway-controlling bulkhead. The end face of the sway-controlling bulkhead is parallel to the cross-section of the liquid container.

[0026] The bulkhead has several through holes 6, and the total area of ​​the through holes is not less than the requirements of the classification society. The Common Structure Specification (HCSR) for bulk carriers and oil tankers requires that the area of ​​the through holes be not less than 10%. In this embodiment, the area of ​​the through holes 6 is 34%.

[0027] Transverse strips 4 and longitudinal strips 5 are laid on the curved bulkhead 2 to maintain its strength and stiffness. The specifications of the strips are determined according to international specifications and standards, as well as numerical simulations. Based on the requirements of the classification society for the strip section modulus, shear area, etc., the specifications of the strips are initially determined and then appropriately adjusted according to the finite element results: the web of the strips is perpendicular to the curved bulkhead; pressure, temperature, and other loads and boundary conditions are applied according to the requirements of the classification society.

[0028] Figure 3 The results are finite element analysis of a curved sway control bulkhead (10mm thick). The stress unit in the figure is Pa. The weight of the curved sway control bulkhead is approximately 16.4 tons. Figure 4 This is the finite element analysis result for a planar sway block (14mm thick), with stress measured in Pa. The weight of the planar block is approximately 17.5 tons. Figure 3 and Figure 4A comparison of finite element results shows that with a wall thickness of 14mm, the maximum stress of a planar bulkhead is 292.85MPa. By changing to a curved surface, the maximum stress can be reduced to 228.22MPa with a wall thickness of only 10mm. The stress distribution of the curved bulkhead is also better than that of the planar bulkhead. Compared to the planar bulkhead, the curved bulkhead weighs approximately 1.1 tons less, and with a reduced wall thickness, the maximum stress is reduced by approximately 22% compared to the planar bulkhead. The curved bulkhead converts the load into pressure along the curved surface, reducing bending moments and fully utilizing the compressive strength of the material; it is also less prone to deformation and damage.

[0029] In this embodiment, the structure described above features high strength, high safety, material saving, and simple structure. The turbulence-controlling bulkhead is connected to the tank body at its ends. The bulkhead has several through holes for liquid flow. The curved shape of the turbulence-controlling bulkhead improves load transfer efficiency, better utilizes the compressive strength of the material, increases structural strength, and reduces the risk of failure. Compared to a flat bulkhead, under the same strength conditions, a curved bulkhead can reduce plate thickness and strip specifications, thereby saving materials and reducing construction costs. The curved structure also facilitates bulkhead inspection and replacement.

[0030] The above embodiments are only used to illustrate the present utility model. Any equivalent transformations and improvements made on the basis of the technical solution of the present utility model shall not be excluded from the protection scope of the present utility model.

Claims

1. A bulkhead structure for LNG ship fuel tanks, characterized in that, In this bulkhead structure, the curved bulkhead (2) is connected to the liquid container wall (3) through the perimeter structure (1). The transverse strips (4) and longitudinal strips (5) on the curved bulkhead (2) form a grid structure. The curved bulkhead (2) is provided with through holes (6) as liquid channels.

2. The bulkhead structure for LNG ship fuel tanks according to claim 1, characterized in that: The web of the transverse strip (4) and longitudinal strip (5) is perpendicular to the curved bulkhead (2).

3. The bulkhead structure for LNG ship fuel tanks according to claim 1, characterized in that: The perimeter structure (1) is an annular plate, and the plate surface of the perimeter structure (1) is perpendicular to and fixedly connected to the liquid container wall (3).

4. The bulkhead structure for LNG ship fuel tanks according to claim 1, characterized in that: The through hole (6) is a circular hole or a fan-shaped hole.

5. The bulkhead structure for LNG ship fuel tanks according to claim 1, characterized in that: The total area of ​​the through hole (6) accounts for 30-40%.

6. The bulkhead structure for LNG ship fuel tanks according to claim 1, characterized in that: The curved bulkhead (2) has a radius of curvature of 10000-15000 mm, a height of 800-1200 mm, and a thickness of 8-15 mm.

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