A solution for expanding the B-type tank in the conversion of container ships into LNG carriers.

Abstract

This invention discloses a B-type hold expansion scheme for converting container ships into LNG carriers, including the structural design of the expanded B-type hold (6.1) within the container ship hold and the design of a hold roof protection structure installed on the top opening of the container ship hold. The expanded B-type hold (6.1) is a hollow, sealed cavity with a rectangular upper part and a trapezoidal lower part designed to avoid the protruding platform (13) of the bilge (2) of the container ship. The hold roof protection structure includes a top sealing plate (5) and a reinforcing beam structure (12) below it. This invention increases the loading capacity of the B-type hold, improves the LNG loading rate, overcomes the torsion problem that easily occurs after the container ship is converted, and improves the overall longitudinal strength of the hull, with huge market prospects and considerable economic benefits.

Description

Technical Field

[0001] This invention relates to the field of large ship conversion technology, and more specifically, to a B-type tank expansion scheme for converting container ships into LNG carriers. Background Technology

[0002] In the early stages of the COVID-19 pandemic, the stagnation of global trade led to a massive backlog of goods. After trade returned to normal, global freight volume surged, resulting in a shortage of container ship capacity and even a shortage of containers, causing container freight rates to skyrocket. Shipowners placed orders for a large number of container ships at shipyards worldwide. However, if the pandemic stabilizes and the backlog of capacity is released, a surplus of container ship capacity will inevitably occur. Container ships are characterized by large openings, high freeboard, and minimal internal structure, providing ample space for flexible conversions. Furthermore, the volatile global situation has highlighted the importance of natural gas, leading to a rising demand for LNG (liquefied natural gas) transport capacity. LNG carriers are expensive to build; therefore, converting large container ships into LNG carriers by incorporating several Type B tanks into these surplus container ships can bring significant economic benefits and simultaneously address the issue of excess container ship capacity.

[0003] like Figure 6 As shown, freeboard 1, bilge 2, bottom 4, standard container 3. Figure 7 As shown, the freeboard 1 of the container ship is high. In order to carry more containers, the container ship has a protruding platform 13 in the bilge 2, on which containers can also be placed.

[0004] However, as Figure 5 As shown, if the existing Type B hold 6 is directly installed inside the container ship's hold, it needs to avoid the protruding platform 13. In this case, the hold capacity utilization rate is low, and the total longitudinal bending stress of the container cross-section is high, resulting in a high total longitudinal bending stress of the container ship. as follows:

[0005] (5)

[0006] Where: F is the axial force acting on the cross section of the container ship, M is the total longitudinal bending moment acting on the cross section, A is the cross-sectional area of ​​the container ship, I is the moment of inertia of the container ship, and dZ is the distance of the container ship from the neutral axis. Summary of the Invention

[0007] The purpose of this invention is to increase the cargo capacity of existing container ships converted into LNG carriers, solve the torsion problem that occurs in the lateral direction of the converted LNG carriers, reduce the total longitudinal bending stress of the cross section, and improve the overall longitudinal strength of the hull.

[0008] To achieve the above objectives, the present invention provides a B-type compartment expansion scheme for converting container ships into LNG carriers, including the structural design of the expanded B-type compartment inside the container ship's hold and the design of the top protection structure installed on the top opening of the container ship's hold.

[0009] The structure of the expanded Type B cabin is as follows:

[0010] The expanded Type B cabin is a hollow, sealed cavity with a rectangular upper section and an inverted trapezoidal lower section that avoids the protruding platform. The distance between the expanded Type B cabin and the apex of the protruding platform is not less than 0.7m; wherein, the inclination angle of the inverted trapezoidal portion of the expanded Type B cabin... α The calculation formula is as follows:

[0011] (1)

[0012] In the formula: d 1—The distance from the apex of the protruding platform to the edge of the expanded Type B cabin;

[0013] d 2—The distance between the sidewall of the prominent platform and the edge of the traditional B-class cabin;

[0014] The expanded Type B cabin provides additional capacity compared to the existing Type B cabin. The calculation formula is as follows:

[0015] (2)

[0016] Where: H is the height of the expanded Type B cabin;

[0017] The difference in width on one side between the expanded Type B cabin and the Type B cabin;

[0018] The width of one side of the existing B-type cabin top bevel;

[0019] H2 is the height of one side of the existing B-type cabin top slope;

[0020] H1 is the height of the section parallel to the freeboard of the expanded Type B cabin;

[0021] The roof protection structure is as follows:

[0022] The top protection structure includes a top sealing plate and a reinforcing beam structure connected to its lower part;

[0023] The reinforcing beam structure includes several transverse beams spaced apart in the transverse direction of the container ship, and four longitudinal ribs spaced apart in the longitudinal direction of the container ship, namely two first longitudinal ribs located near the center of the container ship and two second longitudinal ribs located on the outer sides of the two first longitudinal ribs respectively.

[0024] The total longitudinal bending stress of the container ship section after the addition of the aforementioned top protection structure is shown in the following formula:

[0025] (3)

[0026] In the formula: This represents the increment of the moment of inertia.

[0027] Distance between the dZ neutral axis and the reference axis;

[0028] in, Both dZ and dZ are obtained using the theoretical calculation method of moment of inertia of hull section;

[0029] The increased cross-sectional area of ​​the roof protection structure is calculated using the following formula:

[0030] (4)

[0031] In the formula: B is the width of the top sealing plate section;

[0032] M is the total longitudinal bending moment acting on the cross section, A is the cross-sectional area of ​​the container ship, and I is the moment of inertia of the container ship.

[0033] The height of the first and second longitudinal bones (H3);

[0034] t1 is the thickness of the top sealing plate;

[0035] t2 is the thickness of the first longitudinal bone;

[0036] The thickness of the second longitudinal bone (t3).

[0037] Preferably, the exterior of the expanded Type B compartment is covered with an insulating layer.

[0038] Preferably, the expanded Type B compartment is fixed to the bottom of the ship by a number of bottom support structures arranged in a longitudinal row with intervals between each other.

[0039] Preferably, a number of anti-buoyancy structures are arranged in a longitudinal row and spaced apart from each other on the top of the expanded B-type cabin, with the longitudinal ribs arranged directly above the anti-buoyancy structures on the top of the expanded B-type cabin.

[0040] Preferably, an anti-roll structure is provided at the center of both the bottom and top of the expanded Type B cabin.

[0041] Preferably, an air dome is also required to be installed on top of the expanded Type B cabin.

[0042] Preferably, the top and bottom inner walls of the expanded B-type cabin are provided with several sets of strong frames at intervals, and the reinforcing beam structure is placed above the strong frames.

[0043] Preferably, the cross-section of the strong frame is T-shaped.

[0044] This invention presents a solution for expanding the B-type hold in the conversion of container ships into LNG carriers. By modifying the B-type hold structure, the sidewalls are tilted to eliminate the limitations imposed by the bilge protrusions of the container ship on the B-type hold's layout. Simultaneously, the B-type hold is converted to a flat-top structure, increasing its loading capacity, improving LNG loading efficiency, and achieving higher economic benefits. This invention adds a protective structure to the hold roof, solving the torsional problems that easily occur after container ship conversion, increasing the cross-sectional area and moment of inertia, while reducing the total longitudinal bending stress of the cross-section and improving the overall longitudinal strength of the hull. This invention has enormous market potential and considerable economic benefits. Attached Figure Description

[0045] Figure 1 This is a side view sectional structural diagram of one of the compartments of an LNG carrier modified by the present invention.

[0046] Figure 2 The LNG carrier modified by this invention is in Figure 1 The structural diagram of the cross-section at position AA is shown.

[0047] Figure 3 This is a comparative diagram between the existing B-type cabin structure and the expanded B-type cabin 6.1 structure.

[0048] Figure 4 This is a schematic diagram of the roof protection structure in this invention.

[0049] Figure 5 This is a schematic diagram of the cross-sectional structure of a Type B compartment directly installed into the hold of a container ship in existing technology.

[0050] Figure 6 This is a schematic diagram of the cross-sectional structure of a container ship when it is fully loaded.

[0051] Figure 7 This is a schematic diagram of the cross-sectional structure of a container ship when it is empty.

[0052] Figure 8 yes Figure 2 A magnified structural diagram at point C.

[0053] The components include: 1. Freeboard, 2. Bilge, 3. Standard container, 4. Bottom, 5. Top cap, 6. Type B compartment, 6.1 Expanded Type B compartment, 7. Air dome structure, 8. Vertical support structure, 9. Anti-roll structure, 10. Anti-buoyancy structure, 11. Insulation layer, 12. Reinforcing beam structure, 12.1. Crossbeam, 12.2. Longitudinal rib, 12.21. First longitudinal rib, 12.22. Second longitudinal rib, 13. Projecting platform. Detailed Implementation

[0054] Example:

[0055] A B-type compartment expansion scheme for converting container ships into LNG carriers includes the structural design of the expanded B-type compartment 6.1 inside the container ship's hold and the design of a top protection structure installed on the top opening of the container ship's hold; the top protection structure is used to prevent the upper opening of the container ship from twisting due to low strength.

[0056] like Figures 1-2 As shown, the structure of the expanded Type B cabin 6.1 is as follows:

[0057] The expanded B-type cabin 6.1 is a hollow, sealed cavity with a cuboid upper part and an inverted trapezoidal lower part that avoids the protruding platform 13. Its exterior is covered with an insulating layer 11 for heat insulation.

[0058] The expanded Type B compartment 6.1 is supported and fixed to the hull bottom 4 by thirty-six bottom support structures 8 arranged in four longitudinal rows along the length of the LNG carrier, i.e., nine structures per row with intervals between each pair. Several anti-buoyancy structures 10 are installed on the top of the expanded Type B compartment 6.1, arranged in longitudinal rows with intervals between each pair, to prevent the expanded Type B compartment 6.1 from floating in the event of water ingress.

[0059] To prevent the expanded Type B cabin 6.1 from rolling, an anti-roll structure 9 is installed at the center of both the bottom and top of the expanded Type B cabin 6.1. An air dome 7 is also required to be installed on the top of the expanded Type B cabin 6.1.

[0060] For a strong frame, see CN202010765072.0, "A Novel Type B Independent Storage Tank." A strong frame is a common term in shipbuilding, referring to a strongly supported structure, a frame composed of large-sized components that plays a major supporting role in the structure. Figure 1 The upper and lower sections of the expanded B-type compartment 6.1 have been reinforced with T-shaped profiles, indicating that the liquid tank has a strong frame.

[0061] For anti-buoyancy structure 10, see: CN112356990A - An anti-buoyancy structure for a diamond-shaped liquid cargo tank, CN109484579A - An installation method for an anti-rolling anti-buoyancy device.

[0062] For anti-swaying structure 9, see: CN210942181U - An anti-swaying structure for the top of a liquid tank.

[0063] To increase the capacity of the expanded B-type compartment 6.1, the inclination angle α of the two side walls of the expanded B-type compartment 6.1 is increased, extending obliquely upward towards the protruding platform 13, breaking through the limitation of the protruding platform 13 and increasing the width of the expanded B-type compartment 6.1. At the same time, the top of the expanded B-type compartment 6.1 is designed as a flat roof parallel to the top of the container ship, further expanding the capacity.

[0064] like Figure 8 As shown, the distance between the apex of the expanded Type B cabin 6.1 and the protruding platform 13 is not less than 0.7m; wherein, the inclination angle α of the lower inverted trapezoidal part of the expanded Type B cabin 6.1 is calculated using the following formula:

[0065] (1)

[0066] Where: d1——the distance from the apex of the protruding platform 13 to the edge of the expanded Type B cabin is 6.1m, and not less than 0.7m;

[0067] d2 – The distance between the side wall of protruding platform 13 and the edge of the conventional B compartment is greater than 0.7m.

[0068] The expanded B-type cabin 6.1 provides additional cabin capacity compared to the existing B-type cabin 6. The calculation formula is as follows:

[0069] (2)

[0070] like Figure 3 As shown in the formula: H is the height of the expanded B-type cabin 6.1;

[0071] The difference in width on one side between the expanded B-type cabin 6.1 and the B-type cabin 6;

[0072] The width of one side of the beveled top of the B-type cabin 6;

[0073] H2 is the height of one side of the sloping top of the B-type cabin 6;

[0074] H1 is the height of the section parallel to the freeboard 1 of the expanded B-type cabin 6.1;

[0075] The roof protection structure is as follows:

[0076] like Figure 2 and Figure 4As shown, the reinforcing beam structure 12 includes several transverse beams 12.1 spaced apart in the transverse direction of the container ship, and four longitudinal ribs 12.2 spaced apart in the longitudinal direction of the container ship, namely two first longitudinal ribs 12.21 located near the center of the container ship and two second longitudinal ribs 12.22 located on the outer sides of the two first longitudinal ribs 12.21 respectively. The reinforcing beam structure 12 is arranged above the strong frame of the expanded B-type compartment 6.1, and the longitudinal ribs are arranged directly above the anti-buoyancy structure at the top of the expanded B-type compartment 6.1; the total longitudinal bending stress of the container ship cross-section after the addition of the top protection structure is given by the following formula:

[0077] (3)

[0078] In the formula: This represents the increment of the moment of inertia.

[0079] Distance between the dZ neutral axis and the reference axis;

[0080] Both dZ and dZ are obtained using the theoretical calculation method of moment of inertia of hull section;

[0081] The increased cross-sectional area of ​​the roof protection structure is calculated using the following formula:

[0082] (4)

[0083] like Figure 4 As shown in the formula: B is the width of section 5 of the top sealing plate;

[0084] The height of H3 is 12.21 for the first longitudinal bone and 12.22 for the second longitudinal bone;

[0085] t1 is the thickness of the top sealing plate;

[0086] t2 is the thickness of the first longitudinal bone, which is 12.21.

[0087] The thickness of the second longitudinal bone is 12.22 mm.

[0088] The total longitudinal bending stress σ2 of the container ship after the addition of the top protection structure is less than the total longitudinal bending stress σ1 of the container ship. Therefore, the total longitudinal bending stress of the modified LNG ship hull is reduced and the total longitudinal strength is improved.

[0089] The reinforcing beam structure 12 at the bottom of the top sealing plate 5 improves the torsional strength of the container ship's hold while increasing the cross-sectional area of ​​the hold and improving the overall longitudinal strength.

[0090] This invention converts container ships into LNG carriers, which has huge market potential and considerable economic benefits.

[0091] The above description is only a preferred embodiment of the present invention, but 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 inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for expanding the capacity of a B-type hold applied to a container ship converted into an LNG carrier, characterized by, The application relates to a structure design of an expanded B-type cabin (6.1) in a container ship cabin and a design of a cabin top protection structure installed on a top opening of the container ship cabin. The structure of the expanded B-type cabin (6.1) is as follows: The expansion type B cabin (6.1) is a hollow closed cavity with a rectangular cuboid shape at the upper part and an inverted trapezoidal body shape at the middle and lower parts, and the distance from the expansion type B cabin (6.1) to the top corner of the protruding platform (13) is not less than 0.7 m; wherein the inclination angle of the inverted trapezoidal body shape part of the expansion type B cabin (6.1) is 45°-60°, preferably 45° α The calculation formula is as follows: (1) In the formula: d 1 - distance of the top corner of the protruding platform (13) from the edge of the B-type expanded cabin (6.1); d 2 - distance of the side walls of the protruding platform (13) from the edge of the conventional B cabin; The increased cabin volume of the expanded B-type cabin (6.1) compared with the existing B-type cabin (6) The calculation formula is as follows: (2) H is the height of the expanded B-type cabin (6.1); is the difference in single side width between the expanded B-type cabin (6.1) and the existing B-type cabin (6); to the existing B-type cabin (6) top is cut off the single side width; H2 is the height of a single side of a top bevel of the existing B-type cabin (6); H1 is the height of a parallel section of the expanded B-type cabin (6.1) and a freeboard (1); The cabin top protection structure is as follows: The cabin top protection structure comprises a top sealing plate (5) and a reinforcing beam structure (12) connected to the lower part of the top sealing plate (5); The reinforcing beam structure (12) comprises a plurality of transverse beams (12.1) arranged at intervals in the transverse direction of the container ship and four longitudinal beams (12.2) arranged at intervals in the longitudinal direction of the container ship, wherein the four longitudinal beams (12.2) are two first longitudinal beams (12.21) close to the center of the container ship and two second longitudinal beams (12.22) arranged outside the two first longitudinal beams (12.21) respectively; The total longitudinal bending stress of the container ship after the cabin top protection structure is added is as follows: (3) In the formula: is the moment of inertia increment; dZ is the distance between the neutral axis and the reference axis; wherein, and dZ are both obtained by the theory of ship section inertia moment calculation method; The increased cross-sectional area of the hatch cover protection structure cross section is calculated by the following formula: (4) B is the width of the section of the top sealing plate (5); M is the total longitudinal bending moment acting on the transverse section, A is the section area of the container ship, and I is the moment of inertia of the container ship; H3 is the height of the first longitudinal beam (12.21) and the second longitudinal beam (12.22); t1 is the thickness of the top sealing plate; t2 is the thickness of the first longitudinal beam (12.21); t3 is the thickness of the second longitudinal beam (12.22).

2. The B-type hold expansion method for a container ship converted into an LNG carrier according to claim 1, characterized by, The expanded B-type cabin (6.1) is wrapped with an insulation layer (11) on the outside.

3. The B-type hold expansion method for a container ship converted into an LNG carrier according to claim 1, characterized in that, The expanded B-type cabin (6.1) is fixed to the ship bottom (4) through a plurality of bottom support structures (8) arranged in longitudinal columns and spaced apart from each other.

4. The B-type hold expansion method for a container ship converted into an LNG carrier according to claim 1, characterized in that, A plurality of anti-floating structures (10) arranged in longitudinal columns and spaced apart from each other are arranged at the top of the expanded B-type cabin (6.1), and the longitudinal beams are arranged directly above the anti-floating structures at the top of the expanded B-type cabin (6.1).

5. The B-type hold expansion method for a container ship converted into an LNG carrier according to claim 1, characterized in that, An anti-rolling structure (9) is arranged at the center of the bottom and the top of the expanded B-type cabin (6.1) respectively.

6. The B-type hold expansion method for a container ship converted into an LNG carrier according to claim 1, characterized in that, A dome (7) is arranged at the top of the expanded B-type cabin (6.1).

7. The B-type hold expansion method for a container ship converted into an LNG carrier according to claim 1, characterized in that, A plurality of groups of strong frames are arranged at intervals on the inner wall at the top and the inner wall at the bottom of the expanded B-type cabin (6.1) respectively, and the reinforcing beam structure (12) is arranged above the strong frames.

8. The B-type hold expansion method for a container ship converted into an LNG carrier according to claim 7, characterized in that, The cross section of the strong frame is T-shaped.

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