Method for providing embedded methanol bunker in ultra-large oil tanker

Abstract

A method for providing an embedded methanol bunker in an ultra-large oil tanker. A plurality of rows of cargo holds are provided in a cargo hold area, a middle cargo hold is in the center of each row of cargo holds, a first transverse hold wall (1) is additionally provided in one of the middle cargo holds, and a methanol bunker is provided between the first transverse hold wall (1) and the transverse hold wall (10) of the middle cargo hold. The method comprises: determining the capacity C of the methanol bunker, determining the total length L1 and the width B1 of the methanol bunker for the first time, determining the number Ni of reinforced bulkhead spacings of the cargo hold occupied by the methanol bunker, determining relative positions of a newly added transverse hold wall (5) and a newly added longitudinal hold wall (6), and providing swash bulkheads (2) and cross braces (7) in side cargo holds on the two sides of the middle cargo hold where the methanol bunker is located. The method for providing an embedded methanol bunker in an ultra-large oil tanker can simplify the construction process, reduce the structural weight, reduce the number of members, shorten the construction period, and reduce the weight of an empty tanker.

Description

A method for setting up an embedded methanol fuel tank on a super-large oil tanker Technical Field

[0001] The invention belongs to the field of ship construction and design, and particularly relates to a method for arranging an embedded methanol fuel tank on a super-large oil tanker. Background Art

[0002] With carbon emissions restrictions in place, global green methanol production is on the rise. As a marine fuel, methanol can reduce sulfur oxide (SOx) emissions by approximately 99%, nitrogen oxide (NOx) emissions by 80%, and CO2 emissions by up to 25%. Green methanol has broad global viability as a marine fuel, with 122 of the world's top 100 ports accepting methanol fuel. Drewry predicts that half of ships ordered after 2025 will utilize dual-fuel engines, a significant portion of which will be methanol-powered.

[0003] As of September 2022, Hyundai Shipyard has orders for at least 15 methanol-fueled ships, mainly including MR-type methanol carriers and 16,000TEU container ships. There is no precedent for the application of methanol fuel as the main power on very large oil tankers. The compartment layout of very large oil tankers is different from that of other ship types. Most other ship types have left-right symmetrical compartments. If only the port or starboard cabin is occupied, the ship will tilt. If two cabins are used, two systems need to be equipped, which causes waste. The very large oil tanker has a cross-sectional compartment with three cabins, two side cabins and one middle cabin, which is also the compartment feature of the very large oil tanker. The methanol fuel tank of the present invention is arranged in the middle cabin of the cargo hold, which can save a set of methanol fuel systems and avoid the problem of ship tilting when the methanol fuel tanks are used on both sides.

[0004] Figures 1 to 7 are layout diagrams and typical cross-sectional diagrams of the existing ultra-large oil tanker cargo hold with a cross-bracing structure. Due to the convenience of construction, only one of the cross-bracing methods is usually used for construction. There are currently no ships that use two types of cross-bracing in a cargo hold. There are two types of cross-sectional layouts in the prior art, and this patent uses both types of cross-sectional layouts, and also provides a third type of cross-sectional layout. The first cross-sectional feature is Figure 3, which has the cross brace 7 in the middle cargo hold and the vertical girder 12 is also provided in the middle cargo hold. The second cross-sectional feature is Figure 4, which has the cross brace 7 in the cargo holds on both sides and the vertical girder 12 is also provided in the cargo holds on both sides.

[0005] One difficulty in using methanol fuel tanks on ships is that they take up too much tank space, affecting cargo hold capacity. Another difficulty is that the methanol fuel tank requires special coating. Methanol is corrosive and special coating is expensive, so there needs to be as few components as possible in the tank.

[0006] Summary of the Invention

[0007] To solve the above problems, the present invention provides a method for installing an embedded methanol fuel tank on a very large oil tanker, so as to achieve the purpose of rationally utilizing the original cargo hold structure, optimizing the structural layout, arranging the methanol fuel tank support structure, reducing the increase in structural weight, and reducing the difficulty of construction. The technical solution adopted is:

[0008] A method for arranging an embedded methanol fuel tank on a very large oil tanker, wherein a cargo hold area is provided with multiple rows of cargo holds, the center of each row of cargo holds being a middle cargo hold, side cargo holds being provided on both sides of the middle cargo hold, a first transverse bulkhead being added in one of the middle cargo holds, both ends of the first transverse bulkhead being intersected and fixed with the longitudinal bulkhead of the middle cargo hold, a methanol fuel tank being provided between the first transverse bulkhead and the transverse bulkhead of the middle cargo hold, the methanol fuel tank being a cubic container consisting of two newly added transverse bulkheads and two newly added longitudinal bulkheads, the methanol fuel tank being surrounded by a cofferdam, the original bulkhead of the middle cargo hold and the newly added bulkhead of the methanol fuel tank serving as the bulkhead of the cofferdam, the outer surfaces of the front cofferdam and the rear cofferdam of the methanol fuel tank being provided with horizontal girders, and the specific design method of the methanol fuel tank is as follows:

[0009] S1: Determine the capacity C of the methanol fuel tank

[0010] C={(M / V / d+n)*(P1+P2)+P3} / (ρ*R);

[0011] Where, M is the mileage;

[0012] V is the ship speed;

[0013] d is the number of days;

[0014] P1 is the daily methanol consumption of the generator;

[0015] P2 is the daily methanol consumption of the host;

[0016] P3 is the daily methanol consumption of the boiler;

[0017] n is the reserve amount;

[0018] ρ is the density of methanol;

[0019] R is the fuel filling degree = according to IGF low flash point fuel filling degree is 95% - 2% = 93%.

[0020] S2: Based on the tank capacity C in step S1, the total length L1 and width B1 of the methanol fuel tank are initially determined.

[0021] Methanol fuel tank inner length Ln = C / Ac-2W, m;

[0022] The total length of the methanol fuel tank is L1 = C / Ac = Ln + 2W;

[0023] Wherein, Ac is the cross-sectional area of ​​the methanol fuel tank, Ac=D*B1, m2;

[0024] B1=B-2R,m;

[0025] D is the average net height of the methanol fuel tank, m;

[0026] W is the width of the transverse cofferdam on both sides of the methanol fuel tank, m;

[0027] R is the width of the longitudinal cofferdam on both sides of the methanol fuel tank, m;

[0028] B is the maximum width of the middle cargo hold.

[0029] S3: Determine the number of strong frame spacing Ni of the cargo hold occupied by the methanol fuel tank

[0030] When L1 / S-[L1 / S]≤0, Ni=[L1 / S];

[0031] When L1 / S-[L1 / S]>0, Ni=[L1 / S]+1;

[0032] Where [L1 / S] is the integer part of the calculated value.

[0033] S4: Determine the relative positions of the newly added transverse bulkheads and newly added longitudinal bulkheads.

[0034] When B1>L1, the two ends of the newly added longitudinal bulkhead are respectively intersected and fixed with the first transverse bulkhead and the middle cargo hold transverse bulkhead, and the end of the newly added longitudinal bulkhead is aligned with the stiffener on the first transverse bulkhead; the end of the newly added transverse bulkhead is intersected and fixed with the newly added longitudinal bulkhead;

[0035] When L1≥B1, the two ends of the newly added transverse bulkhead are respectively intersected and fixed with the longitudinal bulkhead of the middle cargo hold; the end of the newly added longitudinal bulkhead is intersected and fixed with the newly added transverse bulkhead, and the end of the newly added longitudinal bulkhead is aligned with the stiffener on the newly added transverse bulkhead;

[0036] The distance between the newly added longitudinal bulkhead and the longitudinal bulkhead of the middle cargo hold is R, R≥600+M, where M is the distance between adjacent stiffeners on the longitudinal bulkhead of the middle cargo hold;

[0037] The distance between the newly added transverse bulkhead and the middle cargo hold transverse bulkhead is W, R ≥ W ≥ 600 + V, where V is the distance between adjacent stiffeners on the middle cargo hold transverse bulkhead;

[0038] At this time, the length of the methanol fuel tank is finally determined to be L11=S*Ni-2W, and the width of the methanol fuel tank is finally determined to be B11=B-2R.

[0039] S5: Swash bulkheads are provided in the side cargo holds on both sides of the middle cargo hold where the methanol fuel tank is located. The swash bulkheads are connected to the first transverse bulkhead, forming continuous bulkheads in the side cargo holds and the middle cargo hold. Horizontal girders are provided on the swash bulkheads, and the number and positions of the horizontal girders on the swash bulkheads are the same as those on the first transverse bulkhead.

[0040] S6: Cross braces are provided.

[0041] The methanol fuel tank divides the original middle cargo hold into a methanol fuel tank area and a cargo hold area, and the swash bulkhead divides the side cargo hold into two areas. The length of the methanol fuel tank area is L2, and the length of the cargo hold area is L3.

[0042] When 2 ≤ Ni ≤ 3,

[0043] L3 > L2, and multiple cross braces are provided in the cargo hold area of the middle cargo hold.

[0044] B1 > L1, the width of the horizontal girder of the first transverse bulkhead is U, T / 2 ≥ U ≥ 600 mm, the width of the horizontal girder of the transverse bulkhead of the middle cargo hold is P, 2T / 3 ≥ P ≥ U, and T is the width of the horizontal girder of the transverse bulkhead of the middle cargo hold.

[0045] When 3 < Ni ≤ 5,

[0046] L3 < L2, and multiple cross braces are provided in the side cargo hold.

[0047] Multiple cross braces are provided in the side cargo hold at the position corresponding to the cargo hold area of the middle cargo hold.

[0048] One cross brace is provided in the side cargo hold at the position corresponding to the methanol fuel tank area of the middle cargo hold, dividing the area corresponding to the methanol fuel tank area into an M area with a length of M and a Q area with a length of Q.

[0049] The length of the methanol fuel tank area is Ni*S.

[0050] 2 ≤ Q ≤ M ≤ 3, Q = 2. If Ni is an even number, one cross brace is provided at Q = Ni*S / 2.

[0051] If Ni is an odd number, one cross brace is provided at Q = (Ni - 1)*S / 2.

[0052] L1 > B1, the width of the horizontal girder of the first transverse bulkhead is U, T / 2 ≥ U ≥ 600 mm, the width of the horizontal girder on the transverse bulkhead of the middle cargo hold is P, 2T / 3 ≥ P ≥ U, and T is the width of the horizontal girder of the transverse bulkhead of the middle cargo hold.

[0053] When 6 ≤ Ni < N - 1,

[0054] L3 ≤ 0.5L2, L1 > B1, the swash bulkhead in the side cargo hold is a double-sided panel, and the cross brace is provided in the methanol fuel tank.

[0055] The length of the methanol fuel tank is Ni*S. Two cross braces divide the side cargo tank into intervals of lengths N, M and Q along the length direction. N≥M≥Q, 2≤Q≤M≤N≤3.

[0056] If Ni is a non-prime number, two cross braces are set at equal intervals in the side cargo hold, and the cross brace panels are facing forward;

[0057] If Ni is a prime number, the cross brace is set at the combination of 2S and 3S, 3S is set close to the sweep bulkhead, and the cross brace panel faces the sweep bulkhead;

[0058] The horizontal girder width of the first transverse bulkhead is U, where T2 / 3 ≥ U ≥ 600mm. The horizontal girder width of the center cargo hold transverse bulkhead is P, where 2T / 3 ≥ P ≥ U, where T is the horizontal girder width of the center cargo hold transverse bulkhead. The T and P values ​​for the three types of cross bracing arrangements differ, and the values ​​vary depending on the arrangement. The horizontal girder supports the transverse bulkhead, while the cross bracing supporting the longitudinal bulkhead is different.

[0059] The above-mentioned method of setting up an embedded methanol fuel tank on a very large oil tanker is further improved. A plurality of rows of cargo holds are set up in the cargo hold area along the length of the ship. Each row of cargo holds is a middle cargo hold and a side cargo hold from the center of the hull to both sides.

[0060] The above method for setting up an embedded methanol fuel tank on a very large oil tanker, further, in step S1, n=3, ρ=0.79t / m3.

[0061] In the above method for providing an embedded methanol fuel tank for a very large oil tanker, further, in step S2, W is initially selected as 1.2 m, and R is initially selected as 1.2 m.

[0062] In the above-mentioned method of setting up an embedded methanol fuel tank on a very large oil tanker, further, the front cofferdam is composed of the first transverse bulkhead, the newly added transverse bulkhead, and the newly added longitudinal bulkhead, and the rear cofferdam is composed of the newly added transverse bulkhead, the middle cargo hold transverse bulkhead, and the newly added longitudinal bulkhead.

[0063] In the above-mentioned method of providing an embedded methanol fuel tank on a very large oil tanker, further, the first transverse bulkhead is fixed to a strong structure of the middle cargo hold.

[0064] In the above-mentioned method for setting up an embedded methanol fuel tank on a very large oil tanker, further, the width of the horizontal girder (3) is designed in accordance with the requirements of Part 2, Chapter 2 Section 3 of the Common Structural Rules for Bulk Carriers and Oil Tankers, an international classification society industry specification, and the number and position of the horizontal girder (3) on the outer surface of the front cofferdam and the rear cofferdam of the methanol fuel tank are the same.

[0065] The above-mentioned method of installing an embedded methanol fuel tank on a very large oil tanker further comprises the following steps: the number of reinforcing ribs on the first transverse bulkhead, the newly added transverse bulkhead, and the middle cargo hold transverse bulkhead, and the spacing between adjacent reinforcing ribs are the same.

[0066] The above method of setting an embedded methanol fuel tank on a super large oil tanker is further described. The methanol fuel tank has a strong frame spacing of S, a strong frame spacing number of N, and 6 <N<10。

[0067] In order to meet the regulatory requirements for double-wall structural protection between the methanol fuel tank and the cargo hold, the present invention fully utilizes the three-sided structural layout characteristics of the very large oil tanker, which has two longitudinal bulkheads and one transverse bulkhead in the cargo hold area, and adds a transverse bulkhead structure in the middle of the middle cargo hold to form an outer wall protected by the double-wall structure; inside the outer wall protected by the double-wall structure, four structural bulkheads of the methanol fuel tank are arranged to form an inner wall protected by the double-wall structure; with the capacity of the methanol fuel tank as the determining factor, by arranging the reinforced structures of the methanol fuel tank, the middle cargo hold and the side cargo hold that meet different capacity requirements, and fully utilizing the layout characteristics of the very large oil tanker, two existing transverse braces and one newly designed transverse brace are selected for combined use, so as to achieve the goal of meeting the structural strength requirements with the least structure, while considering the special coating requirements of the methanol fuel tank, minimizing the components in the tank, reducing the cost of the methanol fuel tank, and taking into account the characteristics of the very large oil tanker. The present invention provides a basis for the design of new ships and a reference for the modification of old ships, simplifies the construction process, reduces the structural weight, reduces the number of components, shortens the construction period, and reduces the empty ship weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG1 is a schematic diagram of the cargo tank structure of an existing ultra-large oil tanker;

[0069] FIG2 is a schematic diagram of the structure of transverse bracing and longitudinal bracing provided in the cargo hold of an existing ultra-large oil tanker;

[0070] Figure 3 is a schematic diagram of the structure of the horizontal and longitudinal braces set in the side cargo hold of an existing ultra-large oil tanker

[0071] FIG4 is a schematic diagram of the structure of the bulkhead corresponding to FIG2;

[0072] FIG5 is a schematic diagram of the structure of the bulkhead corresponding to FIG3;

[0073] FIG6 is a schematic diagram of a horizontal girder structure corresponding to FIG2 ;

[0074] FIG7 is a schematic diagram of a horizontal truss structure corresponding to FIG3;

[0075] FIG8 is a schematic diagram of the structure of the embedded methanol fuel tank located in the middle cargo hold;

[0076] Figure 9 is a schematic diagram of the methanol fuel tank structure when B1>L1;

[0077] Figure 10 is a schematic diagram of the structure of the cross brace provided in the cargo hold;

[0078] Figure 11 is a schematic diagram of the structure of the cross brace provided in the side cargo hold;

[0079] Figure 12 is a schematic diagram of the structure of a partial cross brace provided in the side cargo hold;

[0080] FIG13 is a schematic diagram of the BB perspective structure in FIG10;

[0081] FIG14 is a schematic diagram of the EE perspective structure in FIG10;

[0082] FIG15 is a schematic diagram of the AA viewing angle structure in FIG11;

[0083] FIG16 is a schematic diagram of the BB perspective structure in FIG11;

[0084] FIG17 is a schematic diagram of the EE perspective structure in FIG11;

[0085] FIG18 is a schematic diagram of the GG perspective structure in FIG11;

[0086] FIG19 is a schematic diagram of the AA viewing angle structure in FIG12;

[0087] FIG20 is a schematic diagram of the BB perspective structure in FIG12;

[0088] FIG21 is a schematic diagram of the EE perspective structure in FIG12;

[0089] FIG22 is a schematic diagram of the GG perspective structure in FIG12;

[0090] Figure 23 is a schematic diagram of the methanol fuel tank structure when B1≤L1;

[0091] Including: 1-first transverse bulkhead, 2-swash bulkhead, 3-horizontal girder, 5-new transverse bulkhead, 6-new longitudinal bulkhead, 7-transverse bracing, 8-structure between cofferdam bulkhead and longitudinal bulkhead, 9-horizontal girder corresponding to middle cargo hold transverse bulkhead, 10-middle cargo hold transverse bulkhead, 11-middle cargo hold longitudinal bulkhead, 12-vertical girder. DETAILED DESCRIPTION

[0092] The present invention will be further described with reference to the accompanying drawings.

[0093] As shown in Figure 8, the methanol fuel tank of this patent is installed in the middle cargo hold of a very large oil tanker at the same position. The main advantage is that it will not cause heeling problems as the methanol fuel is consumed, and it will gradually reduce the mid-sag bending moment stress. A design method for an embedded methanol fuel tank in the middle cargo hold of a very large oil tanker is provided. This design method is to set the size of the methanol fuel tank in the middle tank of the very large crude oil tanker according to the tank capacity. Different methanol fuel tank sizes correspond to different numbers of cross bracing reinforcement structures.

[0094] The cargo hold length of the methanol fuel tank is L (m), the spacing between strong frames is S, the number of strong frame spacings is N, and 6 < N < 10. The specific design method is as follows:

[0095] S1: Calculate the volume C of the methanol fuel tank.

[0096] C = {(M / V / d + n) * (P1 + P2) + P3} / (ρ * R).

[0097] Where: M is the mileage.

[0098] V is the ship speed.

[0099] d is the number of days.

[0100] P1 is the daily methanol consumption of the generator.

[0101] P2 is the daily methanol consumption of the main engine.

[0102] P3 is the daily methanol consumption of the boiler.

[0103] n is the reserve, generally taking the methanol fuel consumption for 3 days, which can be adjusted according to the owner's requirements.

[0104] ρ is the methanol density, generally taking 0.79 t / m3, which can be adjusted according to the actual available methanol fuel density of the shipowner.

[0105] R is the fuel fullness = According to the IGF low flash point fuel fullness is 95% - 2% = 93%.

[0106] S2: First determine the total length L1 and width B1 of the methanol fuel tank.

[0107] The inner length of the methanol fuel tank, Ln = C / Ac - 2W, m, and is subsequently corrected to L11.

[0108] The total length of the methanol fuel tank L1 = C / Ac = Ln + 2W.

[0109] C is the volume of the methanol fuel tank in S1, m3.

[0110] Ac is the cross-sectional area of the methanol fuel tank, Ac = D * B1, m2.

[0111] The width of the methanol fuel tank, B1 = B - 2R, m.

[0112] D is the average height of the clean tank of the methanol fuel tank, m.

[0113] W is the width of the lateral isolation tanks on both sides outside the methanol fuel tank, m, initially taken as 1.2 m first and subsequently corrected to L11.

[0114] R is the width of the longitudinal cofferdam on both sides of the methanol fuel tank, in m. It is initially taken as 1.2 meters and subsequently revised to B11.

[0115] S3: Determine the number Ni of strong frame spacings in the cargo hold occupied by the methanol fuel tank.

[0116] Where Ni = [L1 / S], when L1 / S-[L1 / S]≤0.

[0117] Ni=[L1 / S]+1, when L1 / S-[L1 / S]>0.

[0118] Where [L1 / S] is the integer part of the calculated value.

[0119] S4: Determine Ni and select the cargo hold cross brace.

[0120] When 2≤Ni≤3, proceed to S5, S6, and S7.

[0121] When 3<Ni≤5, proceed to S5, S6, and S8.

[0122] When 5<Ni≤N-1, perform S5, S6, and S9.

[0123] L2=Ni*S.

[0124] S5: Embedded methanol fuel tank structure design.

[0125] The embedded methanol fuel tank structure design includes the first transverse bulkhead 1 of the double-wall methanol fuel tank structure, the horizontal girder 3 supporting the first transverse bulkhead 1 of the outer wall structure, the horizontal girder 10 of the middle cargo hold transverse bulkhead optimized by the double-wall structure, the inner wall structure of the double-wall methanol fuel tank structure with a newly added transverse bulkhead 5, the inner wall structure of the double-wall methanol fuel tank structure with a newly added longitudinal bulkhead 6, and the double-wall middle vertical support structure 8 of the double-wall methanol fuel tank structure without the transverse bracing material 7. That is, no transverse bracing structure is set in the methanol fuel tank, and a quasi-clean tank design is adopted.

[0126] The first transverse bulkhead 1 of the outer wall structure of the double-wall methanol fuel tank structure is located within the middle cargo hold. Together with the three existing structures of the cargo hold area, namely, two longitudinal bulkheads 11 and one middle cargo hold transverse bulkhead 10, they form the outer wall structure of the double-wall methanol fuel tank structure. Since the middle cargo hold transverse bulkhead 10 is provided with a horizontal girder 9 supporting the transverse bulkhead forward, the first transverse bulkhead 1 is located aft of the target middle cargo hold to reduce the internal structure of the methanol fuel tank. The first transverse bulkhead 1 is located at the middle cargo hold's strong structure, with a distance L2 from the original middle cargo hold transverse bulkhead 10. To facilitate construction, the stiffener structure layout and spacing on the first transverse bulkhead 1 of the outer wall structure are the same as those of the original middle cargo hold transverse bulkhead 10, and the stiffener structure is arranged aft of the first transverse bulkhead 1 of the outer wall structure.

[0127] As the first transverse bulkhead 1 of the outer wall structure requires a longitudinal strong support, a horizontal girder 3 is provided on the rear side of the first transverse bulkhead 1 of the outer wall structure. As the first transverse bulkhead 1 of the outer wall structure and the methanol fuel tank wall 5 form a double-wall structure, the strength is greater than that of the original middle cargo hold transverse bulkhead 10. Therefore, the width of the horizontal girder 3 is U, which is designed in accordance with the requirements of Part 2, Chapter 2 Section 3 of the Common Structural Rules for Bulk Carriers and Oil Tankers of the international classification society industry standard. The number and height position of the horizontal girder 3 are consistent with the horizontal girder 9 of the original middle cargo hold transverse bulkhead 10, forming a longitudinal continuous support and effectively transmitting the longitudinal load.

[0128] Since the middle cargo hold transverse bulkhead 10 and the methanol fuel tank wall 5 form a double-wall structure and are stronger than the middle cargo hold transverse bulkhead 10, the double-wall structure can be used to optimize the width of the horizontal girder. Since the original middle cargo hold transverse bulkhead 10 also supports the transverse bulkheads of the left and right cargo holds, the width of the horizontal girder 4 of the middle cargo hold transverse bulkhead 10 is P, which is designed in accordance with the requirements of Part 2, Chapter 2 Section 3 of the Common Structural Rules for Bulk Carriers and Oil Tankers, an international classification society industry standard.

[0129] The embedded methanol fuel tank is initially designed to be L1 in length and B1 in width.

[0130] When B1>L1, as shown in Figure 9, a methanol fuel tank longitudinal bulkhead 6 is installed inside the original two longitudinal bulkheads 11. The left and right endpoints of the longitudinal bulkhead 6 are located at the first transverse bulkhead 1 and the middle cargo hold transverse bulkhead 10, and the endpoints align with the reinforcement ribs on the first transverse bulkhead 1. A methanol fuel tank transverse bulkhead 5 is installed inside the first transverse bulkhead 1 and the middle cargo hold transverse bulkhead 10, with the left and right endpoints of the transverse bulkhead 5 located at the methanol fuel tank longitudinal bulkhead 6. This shortens the transverse length of the methanol fuel tank transverse bulkhead 5, optimizes the structure, and reduces weight.

[0131] When L1 ≥ B1, as shown in FIG23 , a methanol fuel tank transverse bulkhead 5 is provided on the inner side of the first transverse bulkhead 1 and the middle cargo hold transverse bulkhead 10, with the left and right endpoints of the transverse bulkhead 5 being provided at the methanol fuel tank longitudinal bulkhead 11, thereby shortening the longitudinal length of the methanol fuel tank longitudinal bulkhead 6, optimizing the structure, and reducing the weight; a methanol fuel tank longitudinal bulkhead 6 is provided on the inner side of the original two longitudinal bulkheads 11, with the left and right endpoints of the longitudinal bulkhead 6 being provided at the methanol fuel tank inner wall 5, and aligned with the reinforcing ribs on the transverse bulkhead 5 at the endpoints;

[0132] To facilitate construction, the arrangement and spacing of the reinforcing rib structure on the methanol fuel tank longitudinal bulkhead 6 are the same as those of the original longitudinal bulkhead 11, and the reinforcing rib structure is arranged on the outside of the methanol fuel tank longitudinal bulkhead 6; since an inspection passage needs to be arranged between the methanol fuel tank longitudinal bulkhead 6 and the original longitudinal bulkhead 11, and the reinforcing rib structure of the methanol fuel tank longitudinal bulkhead 6 and the original longitudinal bulkhead 11 also needs to be arranged, the distance R between the methanol fuel tank longitudinal bulkhead 6 and the original longitudinal bulkhead 11 is R≥600+M, where M is the spacing between the reinforcing ribs of the longitudinal bulkhead 11. The arrangement and spacing of the reinforcing rib structure on the methanol fuel tank transverse bulkhead 5 are the same as those of the original middle cargo hold transverse bulkhead 10, and the reinforcing rib structure is arranged on the outside of the methanol fuel tank transverse bulkhead 5. Since an inspection passage needs to be arranged between the methanol fuel tank transverse bulkhead 5 and the original middle cargo hold transverse bulkhead 10, and the reinforcing rib structure of the methanol fuel tank transverse bulkhead 5 also needs to be arranged, the distance W between the methanol fuel tank transverse bulkhead 5 and the original middle cargo hold transverse bulkhead 10 is R≥W≥600+V, where V is the spacing between the reinforcing ribs of the original middle cargo hold transverse bulkhead 10.

[0133] The length of the embedded methanol fuel tank was finally revised to L11=S*Ni-2W, and the width was B11=B-2R.

[0134] S6: Swash bulkhead installation.

[0135] The function of a sloshing bulkhead is to reduce the sloshing force of the cargo hold and to support the two longitudinal bulkheads, minimizing deformation. According to regulatory requirements, if the distance between the sloshing bulkhead and the cargo hold bulkhead exceeds 35 meters, a sloshing bulkhead must be added to the cargo hold. Based on the structural design features and positional relationship of the sloshing bulkhead, the present invention repositions the sloshing bulkhead to align with the newly added transverse bulkhead structure, forming a transversely penetrating support structure. This also meets the requirement that the distance between the sloshing bulkhead and the cargo hold bulkhead does not exceed 35 meters, eliminating the need for an additional sloshing bulkhead structure.

[0136] Because the first transverse bulkhead 1 of the outer wall structure requires a corresponding transverse support in the port and starboard cargo holds, to optimize the structural layout and reduce weight, the sweep bulkhead 2 was relocated so that its position coincides with that of the first transverse bulkhead 1 of the outer wall structure. This creates a transverse support structure that runs through the port and starboard cargo holds. The load from the first transverse bulkhead 1 of the outer wall structure can be effectively transferred to the double-side structure through the sweep bulkhead 2, thereby reducing stress levels. Furthermore, the first transverse bulkhead 1 of the outer wall structure also reduces stress on the ends of the sweep bulkhead 2, enhancing structural safety.

[0137] S7: When 2 ≤ Ni ≤ 3, the cargo hold is divided into two areas. The length of the methanol fuel tank area is L2, and the length of the cargo hold area is L3, where L3 > L2. In area L3, from the tail of the cargo hold to the section inside the stop bulkhead, the traditional intermediate transverse brace support scheme is adopted. Since the methanol fuel tank is relatively small and has a double bulkhead design, the transverse braces on the side cargo hold corresponding to the methanol fuel tank are cancelled. Horizontal girder structure diagram 7.

[0138] B1 > L1. The longitudinal bulkhead of the methanol fuel tank is arranged between bulkheads 1 and 10, and the transverse bulkhead of the methanol fuel tank is arranged between bulkheads 5. Among them, the first transverse hold bulkhead 1 of the outer wall structure is aligned with the stop bulkhead, and the panel structure on the stop bulkhead is arranged behind the hold, which can shorten the longitudinal span of the side cargo hold. The width of the horizontal girder 3 is U, where T / 2 ≥ U ≥ 600 mm, and the width of the horizontal girder 4 is P, where 2T / 3 ≥ P ≥ U, and T is the width of the horizontal girder 9 of the original middle cargo hold transverse bulkhead 10.

[0139] S8: When 3 < Ni ≤ 5, L3 < L2. From the tail of the cargo hold to the section inside the stop bulkhead in area L3, the transverse brace support structure with transverse braces arranged on both side holds in the traditional design is adopted. Since L1 > B1, the transverse bulkhead 5 of the methanol fuel tank is arranged between the continuous longitudinal bulkheads 11, and the longitudinal bulkhead 6 of the methanol fuel tank is arranged between the transverse bulkheads 5 of the methanol fuel tank, effectively reducing the span of the longitudinal bulkhead 6 of the methanol fuel tank. The panel direction of the transverse brace structure faces the bow, so that the panel of the transverse brace structure can effectively support the transverse bulkhead 5 of the methanol fuel tank. The length of the large bracket of the transverse brace panel is greater than the spacing W of the methanol fuel tank.

[0140] Since the length of the methanol fuel tank is relatively large, although it has a double-wall structure, transverse braces still need to be arranged in the methanol fuel tank.

[0141] The length of the methanol fuel tank is Ni * S. The side hold is divided into intervals with lengths M and Q along the length direction, where M ≥ Q.

[0142] 2 ≤ Q ≤ M ≤ 3, and Q is preferably 2. If Ni is an even number, the transverse brace is arranged at Q = Ni * S / 2, that is, in the middle of the hold, and the panel direction of the transverse brace faces forward. If Ni is an odd number, the transverse brace is arranged at Q = (Ni - 1) * S / 2, that is, the distance from the transverse brace arrangement position to the front bulkhead is Q. Since M ≥ Q, the panel direction faces backward, reducing the longitudinal span of the large spacing. The width of the horizontal girder 3 is U, where T / 2 ≥ U ≥ 600 mm, and the width of the horizontal girder 4 is P, where 2T / 3 ≥ P ≥ U, and T is the width of the horizontal girder 9 of the original middle cargo hold transverse bulkhead 10;

[0143] Figure 12 shows the unique support structure of this patented VLCC. Unlike the two transverse bracing structures used in conventional designs, it utilizes large brackets directly between the inner hull and longitudinal bulkheads. This eliminates the traditional vertical girders between the side cargo holds and places them between the double bulkheads of the methanol fuel tank. This reduces the number of components and simplifies the construction process while ensuring strength requirements. Bulkhead 1 is consistent with Figure 9.

[0144] S9: When 6≤Ni<N-1, L3≤0.5L2, the cross bracing support structure is eliminated from the section from the cargo hold tail to the stop bulkhead. Since L1>B1 of the methanol fuel tank, a two-way panel is provided on the stop bulkhead. In this way, the cross bracing structure panel can effectively support the transverse bulkhead 5 of the methanol fuel tank. The length of the large bracket of the cross bracing panel is greater than the spacing W between the methanol fuel tanks.

[0145] Since the methanol fuel tank is relatively long, although it has a double-wall structure, cross braces still need to be installed in the methanol fuel tank.

[0146] The length of the methanol fuel tank is Ni*S, and the side tanks are divided into intervals of length N, M and Q along the length direction, N≥M≥Q, 2≤Q≤M≤N≤3. If Ni is a non-prime number, the cross braces are set at equal intervals, that is, the side cargo tanks are supported at equal intervals, and the cross brace panels are facing forward. If Ni is a prime number, the cross brace is set at the combination of 2S and 3S, and 3S is set at a position close to the stop bulkhead, with the panel facing the stop bulkhead to reduce the longitudinal span of the large interval. The width of the horizontal girder 3 is U, T2 / 3≥U≥600mm, and the width of the horizontal girder 4 is P, 2T / 3≥P≥U, and T is the width of the horizontal girder 9 of the original middle cargo hold transverse bulkhead 10;

[0147] As shown in Figure 13, the unique support structure of this patented VLCC differs from the two transverse bracing structures used in conventional designs. It utilizes large brackets directly between the inner hull and longitudinal bulkheads, eliminating the traditional vertical girders between the wing cargo holds. Instead, the vertical girders are located between the double bulkheads of the methanol fuel tank. This reduces the number of components and simplifies the construction process while ensuring strength requirements. Bulkhead 1 is consistent with Figure 9. In the L2 area, transverse bracing is eliminated and supported by circular panels, saving lightship weight.

[0148] Since the side cargo hold in the L2 area is longer, a C-shaped reinforcement frame is set between the newly designed cross braces 14 to prevent the liquid in the cargo hold from sloshing.

[0149] S10: The final methanol fuel tank capacity is C1, C1 = L11*B11*D.

[0150] When C1 / C>95%, output the solution.

[0151] When C1 / C<95%, the width of the isolation cabin needs to be modified to meet the requirements.

[0152] If modifying the isolation tank to the minimum size still does not meet the requirements, then the number of existing strong frames Ni+1 needs to be increased and redesigned.

[0153] Taking a certain ship as an example

[0154] C = ((12000÷15÷24 + 3)×(13.3 + 125.3) + 350)÷(0.79×93%) = 7330m 3 .

[0155] Ac = D×B1 = 28.6×(20.4 - 1.2×2) = 514.8m 2 .

[0156] B1 = 18m.

[0157] Ln = 7330÷514.8 = 14.2.

[0158] L1 = 14.2 + 1.2×2 = 十六点六米。

[0159] S = 5.670m.

[0160] L1 / S = 16.6÷5.67 = 2.93. After taking the integer, Ni = 3, that is, the methanol fuel tank occupies the space of the cargo hold area with a length of 3 strong frame spacings. <s

[0161] Ln < B1, the new bulkhead 6 starts from bulkhead 1 and bulkhead 10.

[0162] Among them, U = 1.9m; W = 1.4m, R = 1.4m, P = 2.0m.

[0163] Finally, L11 = 3×5.67 - 2×1.4 = 14.21m.

[0164] B11 = 20.4 - 2×1.4 = 17.6m.

[0165] C1 = L11×B11×D = 7152.7m 3 .

[0166] C1 / C = 7152.7÷7330 = 97.6% > 95%, meeting the requirements.

Claims

1. A method for installing an embedded methanol fuel tank on a very large oil tanker, characterized in that: The cargo hold area is provided with multiple rows of cargo holds, the center of each row of cargo holds is the middle cargo hold, and side cargo holds are provided on both sides of the middle cargo hold. A first transverse bulkhead is added in one of the middle cargo holds, and both ends of the first transverse bulkhead are intersected and fixed with the longitudinal bulkhead of the middle cargo hold. A methanol fuel tank is provided between the first transverse bulkhead and the transverse bulkhead of the middle cargo hold. The methanol fuel tank is a cubic container composed of two newly added transverse bulkheads and two newly added longitudinal bulkheads. The methanol fuel tank is surrounded by an isolation tank. The original bulkhead of the middle cargo hold and the newly added bulkhead of the methanol fuel tank serve as the bulkhead of the isolation tank. The outer surfaces of the front isolation tank and the rear isolation tank of the methanol fuel tank are provided with horizontal beams. The specific design method of the methanol fuel tank is as follows: S1: Determine the capacity C of the methanol fuel tank Where, M is the mileage; V is the ship speed; d is the number of days; P1 is the daily methanol consumption of the generator; P2 is the daily methanol consumption of the main engine; P3 is the daily methanol consumption of the boiler; n is the reserve amount; is the density of methanol; R is the fuel filling degree = according to IGF low flash point fuel filling degree is 95%-2%=93%; S2: According to the tank capacity C in step S1, the total length L1 and width B1 of the methanol fuel tank are first determined The length of methanol fuel tank Ln=C / Ac-2W, m; The total length of the methanol fuel tank is L1 = C / Ac = Ln + 2W; Wherein, Ac is the cross-sectional area of ​​the methanol fuel tank, Ac = D*B1, m2; B1=B-2R,m; D is the average net height of the methanol fuel tank, m; W is the width of the transverse cofferdam on both sides of the methanol fuel tank, m; R is the width of the longitudinal cofferdam on both sides of the methanol fuel tank, m; B is the maximum width of the middle cargo hold; S3: Determine the number of strong frame spacing Ni of the cargo hold occupied by the methanol fuel tank When L1 / S-[L1 / S]≤0, Ni=[L1 / S]; When L1 / S-[L1 / S]>0, Ni=[L1 / S]+1; Wherein, [L1 / S] is the integer part of the calculated value; S4: Determine the relative positions of the newly added transverse bulkheads and the newly added longitudinal bulkheads When B1>L1, the two ends of the newly added longitudinal bulkhead are respectively intersected and fixed with the first transverse bulkhead and the middle cargo hold transverse bulkhead, and the end of the newly added longitudinal bulkhead is aligned with the stiffener on the first transverse bulkhead; the end of the newly added transverse bulkhead is intersected and fixed with the newly added longitudinal bulkhead; When L1≥B1, the two ends of the newly added transverse bulkhead are respectively intersected and fixed with the longitudinal bulkhead of the middle cargo hold; the end of the newly added longitudinal bulkhead is intersected and fixed with the newly added transverse bulkhead, and the end of the newly added longitudinal bulkhead is aligned with the stiffener on the newly added transverse bulkhead; The distance between the newly added longitudinal bulkhead and the longitudinal bulkhead of the middle cargo hold is R, R≥600+M, where M is the distance between adjacent stiffeners on the longitudinal bulkhead of the middle cargo hold; The distance between the newly added transverse bulkhead and the middle cargo hold transverse bulkhead is W, R≥W≥600+V, where V is the distance between adjacent stiffeners on the middle cargo hold transverse bulkhead; At this time, the length of the methanol fuel tank is finally determined to be L11 = S*Ni-2W, and the width of the methanol fuel tank is finally determined to be B11 = B-2R; S5: Swash bulkheads are provided in the side holds on both sides of the middle hold where the methanol fuel tank is located. The swash bulkheads are connected to the first transverse bulkhead, forming continuous bulkheads in the side holds and the middle hold. Horizontal girders are provided on the swash bulkheads, and the number and positions of the horizontal girders on the swash bulkheads are the same as those on the first transverse bulkhead. S6: Provide cross braces The methanol fuel tank divides the original middle hold into a methanol fuel tank area and a cargo hold area. The swash bulkheads divide the side holds into two areas. The length of the methanol fuel tank area is L2, and the length of the cargo hold area is L3. When 2 ≤ Ni ≤ 3, L3 > L2, and multiple cross braces are provided in the cargo hold area of the middle hold. B1 > L1, the width of the horizontal girder of the first transverse bulkhead is U, T / 2 ≥ U ≥ 600 mm, the width of the horizontal girder of the transverse bulkhead of the middle hold is P, 2T / 3 ≥ P ≥ U, where T is the width of the horizontal girder of the transverse bulkhead of the middle hold. When 3 < Ni ≤ 5, L3 < L2, and multiple cross braces are provided in the side hold. Multiple cross braces are provided in the side hold at the position corresponding to the cargo hold area of the middle hold. One cross brace is provided in the side hold at the position corresponding to the methanol fuel tank area of the middle hold, dividing the area corresponding to the methanol fuel tank area into an M area with a length of M and a Q area with a length of Q. The length of the methanol fuel tank area is Ni*S. 2 ≤ Q ≤ M ≤ 3, Q = 2. If Ni is an even number, one cross brace is provided at Q = Ni*S / 2. If Ni is an odd number, one cross brace is provided at Q = (Ni - 1)*S / 2. L1 > B1, the width of the horizontal girder of the first transverse bulkhead is U, T / 2 ≥ U ≥ 600 mm, the width of the horizontal girder on the transverse bulkhead of the middle hold is P, 2T / 3 ≥ P ≥ U, where T is the width of the horizontal girder 9 of the original transverse bulkhead 10 of the middle hold. When 6 ≤ Ni < N - 1, L3 ≤ 0.5*L2, L1 > B1, the swash bulkhead in the side hold is a two-way panel, and the cross braces are provided in the methanol fuel tank. The length of the methanol fuel tank is Ni*S. Two cross braces divide the side hold into intervals with lengths of N, M, and Q along the length direction, N ≥ M ≥ Q, 2 ≤ Q ≤ M ≤ N ≤ 3. If Ni is a non-prime number, the two cross braces are provided at equal intervals in the side hold, and the cross brace panel faces forward. If Ni is a prime number, the cross braces are provided at the combined positions of 2S and 3S, with 3S located closer to the swash bulkhead, and the cross brace panel faces the swash bulkhead. The width of the horizontal girder of the first transverse bulkhead is U, T2 / 3 ≥ U ≥ 600 mm, the width of the horizontal girder on the transverse bulkhead of the middle hold is P, 2T / 3 ≥ P ≥ U, where T is the width of the horizontal girder of the original transverse bulkhead of the middle hold.

2. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: Multiple rows of cargo holds are provided along the length direction of the cargo hold. For each row of cargo holds, from the center of the hull to both sides, there are the middle hold and the side hold in sequence.

3. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: In step S1, n=3, 4. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: In step S2, W is first selected as 1.2 m, and R is first selected as 1.2 m.

5. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: The front isolation tank is composed of the first transverse bulkhead, the newly added transverse bulkhead, and the newly added longitudinal bulkhead. The rear isolation tank is composed of the newly added transverse bulkhead, the transverse bulkhead of the middle hold, and the newly added longitudinal bulkhead.

6. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: The first transverse bulkhead is fixed at the strong structure of the middle hold.

7. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: The width of the horizontal girder (3) is designed in accordance with the requirements of Part 2, Chapter 2 Section 3 of the Common Structural Rules for Bulk Carriers and Oil Tankers, an international classification society industry specification. The number and position of the horizontal girder (3) on the outer surface of the front cofferdam and the rear cofferdam of the methanol fuel tank are the same.

8. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: The number of stiffeners and the spacing between adjacent stiffeners on the first transverse bulkhead, the newly added transverse bulkhead and the mid cargo hold transverse bulkhead are the same.

9. The method for installing an embedded methanol fuel tank on a very large oil tanker according to claim 1, characterized in that: The strong frame spacing of the methanol fuel tank is S, the number of strong frame spacing is N, 6 <N<10。

Images