A method for expanding the capacity of a methanol tank

Abstract

A methanol tank expansion method, a first transverse bulkhead is added between two transverse bulkheads, the first transverse bulkhead extends through the inner shell plate of the hull to the outermost shell plate of the hull, two second transverse bulkheads are arranged between the transverse bulkhead and the first transverse bulkhead, and the two second transverse bulkheads extend to the inner shell plate of the hull, one of the second transverse bulkheads and the transverse bulkhead and the inner shell plate of the hull form a front isolation tank, and the other second transverse bulkhead and the first transverse bulkhead and the inner shell plate of the hull form a rear isolation tank. The present application can divide the methanol tank into multiple tanks by arranging a groove-shaped bulkhead in the cargo tank area. The tank is a clean tank (without any components), which is convenient for washing the cargo tank. After washing, other conventional fuels (fuel oil or diesel oil), oil liquid cargo or chemical liquid cargo can be loaded, which has strong versatility and flexibility. The longitudinal members are continuous, the ballast water tank can be used as an isolation empty tank, and when the methanol tank is not used as a methanol tank, the ballast water tank can be used normally.

Description

Technical Field

[0001] The present invention belongs to the field of shipbuilding and design, and particularly relates to a method for expanding the capacity of a methanol tank. Background Art

[0002] On January 17, 2020, the world's first large-scale solar fuel synthesis demonstration project was officially put into operation in Lanzhou, China, marking China's official large-scale production of green methanol fuel using renewable energy. As a carbon-neutral fuel, green methanol has attracted much attention in the shipping industry in order to achieve more carbon emission reduction effects.

[0003] Mass energy density and volume energy density are important indicators for evaluating the applicability of alternative fuels in shipping, and another important indicator is the storage environmental conditions. Methanol fuel can be stored in liquid state at normal temperature and pressure, with good economy, so it is highly favored. At the same time, methanol fuel has characteristics such as low flash point, easy evaporation, low boiling point (64.7 °C), and toxicity. When used as a marine fuel, it needs to comply with specifications such as MSC.1 / Circ.1621 and IGF Code. According to the specification requirements, isolation void spaces should be arranged around the integral methanol fuel tank, and currently, inorganic zinc silicate coatings are used inside the methanol tanks of mature products on the market. The special coating process requirements are very strict, and large-sized components are not suitable to be arranged inside the tank. Therefore, the layout space of the isolation void spaces around the methanol fuel tank not only needs to meet the minimum distance required by the specifications, but also needs to consider the structural layout space requirements. For all the above reasons, the space required for the layout of the methanol fuel tank is relatively large. The volume ratio coefficient compared with MGO fuel is about 2.44, and the volume ratio coefficient compared with LNG fuel is about 1.4. Therefore, in order to meet the requirement of greater endurance, the methanol fuel tank is usually selected to be arranged in the cargo hold area.

[0004] As Figure 1 、 2 shown, to implement the methanol dual-fuel solution, the methanol tank is arranged in the mid-cargo hold, and the methanol tank is distributed longitudinally. Since methanol fuel is a dangerous substance, isolation void spaces need to be added in the mid-cargo hold. As Figure 3 、 4 shown, a bulkhead 100 is added in front of and behind the transverse bulkhead 5 respectively, with a spacing of A, 600 mm < A < 1500 mm. A longitudinal bulkhead 101 is added on the left and right sides of the longitudinal bulkhead 4 respectively, with a spacing of B, 600 mm < B < 1500 mm. A bulkhead 102 is added upward from the inner bottom, with a spacing of C, 600 mm < C < 1500 mm. The space formed by the added bulkheads and the original transverse and longitudinal bulkheads is the isolation void space 6, and the area formed by the newly added bulkheads and the deck is the methanol tank 7 (the area enclosed by the solid line). The existing design needs to occupy one cargo hold, that is, the hold capacity of one cargo hold is lost.

[0005] The problem lies in:

[0006] 1. There is currently no guidance on how to design a methanol tank.

[0007] 2. For newly designed ships and converted ships, adding a methanol tank in the cargo hold area will result in a loss of a part of the cargo hold capacity, leading to a reduction in the loading volume.

[0008] 3. Usually, a ship has a single tank, with poor flexibility. Since methanol is corrosive and toxic, it cannot be used once a leakage problem occurs. Summary of the Invention

[0009] To solve the above problems, the present invention provides a method for expanding the capacity of a methanol tank. The technical solution adopted is as follows:

[0010] A method for expanding the capacity of a methanol tank. The hull has a double - skin outer plate and a double - bottom ship plate. Inside the hull, transverse bulkheads and longitudinal bulkheads are provided. The transverse bulkheads and longitudinal bulkheads enclose a cargo hold area. In the cargo hold area, from the center of the hull to the side, there are a middle cargo hold, a side cargo hold, and a ballast water tank in sequence. It is characterized in that a methanol fuel tank is arranged along the ship width direction. The specific setting method is as follows:

[0011] Add a first transverse bulkhead between two transverse bulkheads. Both ends of the first transverse bulkhead pass through the inner - layer shell outer plate of the hull and extend to the outermost - layer shell outer plate of the hull. The first transverse bulkhead is parallel to the transverse bulkhead.

[0012] There are two second transverse bulkheads between the transverse bulkhead and the first transverse bulkhead. Both ends of the second transverse bulkheads extend to the inner - layer shell outer plate of the hull. One of the second transverse bulkheads forms a front isolation tank with the transverse bulkhead and the inner - layer shell outer plate of the hull, and the other second transverse bulkhead forms a rear isolation tank with the first transverse bulkhead and the inner - layer shell outer plate of the hull.

[0013] The two second transverse bulkheads and the inner - layer shell outer plate of the hull form a methanol fuel tank. The ballast water tanks on both sides are used as lateral isolation void spaces for the methanol fuel tank.

[0014] In the methanol fuel tank, corrugated bulkheads are provided. The distance between the intersections of the inner shells on both sides of the methanol fuel tank and the deck is D. When 0 < D < 20m, the number of longitudinally - divided corrugated bulkheads is 0. When 20 < D < 30m, the number of longitudinally - divided corrugated bulkheads is 1. When 30 ≤ D < 60m, the number of longitudinally - divided corrugated bulkheads is 2. The length of the methanol tank separated by the corrugated bulkhead is L1. When L1 < 16m, the corrugated bulkhead is set as a horizontal groove. When the length of the methanol tank L1 ≥ 16m, the corrugated bulkhead is set as a vertical groove.

[0015] The corrugated bulkhead has upper and lower wall piers. In the case of a vertical groove, the height of the lower wall pier is consistent with the highest point of the internal fold angle of the tank and does not exceed one - third of the height of the corrugated bulkhead. There is a distance M between the inclined plate of the lower wall pier and the bottom longitudinal girder, 300 < M < 1000mm, or M is equal to the distance between the bottom longitudinal members.

[0016] Furthermore, in the aforementioned method for expanding the methanol tank, longitudinal ribs are provided on the transverse bulkhead, the first transverse bulkhead, and the two second transverse bulkheads, with the longitudinal ribs located in the front isolation compartment and the rear isolation compartment.

[0017] Furthermore, in the aforementioned method for expanding the methanol tank, the internal distance between the front isolation chamber and the rear isolation chamber is 1200–2000 mm.

[0018] Furthermore, in the above-mentioned methanol tank expansion method, when the tank is vertical, the height of the upper wall pier is less than the height of the lower wall pier, and the height of the upper wall pier is no more than one-quarter of the height of the tank wall.

[0019] In a further step, in the case of a horizontal tank, the upper and lower wall blocks are respectively installed in the front and rear isolation compartments of the methanol fuel tank.

[0020] Furthermore, in the aforementioned method for expanding the methanol tank, the number of longitudinally segmented trough-shaped tank walls within the methanol fuel tank is no more than three.

[0021] Furthermore, in the aforementioned method for expanding the methanol tank, the height of the upper wall pier is less than the height of the lower wall pier, and the height of the upper wall pier is no more than one-quarter of the height of the tank wall.

[0022] Furthermore, in the above-mentioned method for expanding the methanol tank, the number of tank walls is no more than 2.

[0023] Furthermore, in the aforementioned method for expanding the methanol tank, a longitudinally segmented trough-shaped bulkhead divides the methanol fuel tank into two methanol tanks.

[0024] Furthermore, in the aforementioned method for expanding the methanol tank, the walls of the front and rear isolation chambers are equipped with longitudinal ribs that are aligned, with a minimum distance of 700 mm between the aligned longitudinal ribs.

[0025] This invention utilizes a trough-shaped bulkhead in the cargo hold area to divide the methanol tank into multiple compartments. These compartments are clean (without any structural components), facilitating tank cleaning. After cleaning, they can be used to load other conventional fuels (fuel oil or diesel), oily liquids, or chemical liquids, offering strong versatility and flexibility. Maintaining longitudinal structural continuity, the ballast water tank can also be used as an isolation compartment. When the methanol tank is not being used as a methanol tank, the ballast water tank can be used normally. Attached Figure Description

[0026] Figure 1 A top view of an existing double-hull, double-bottom, double-longitudinal bulkhead ship type;

[0027] Figure 2 for Figure 1 A schematic diagram of the AA perspective;

[0028] Figure 3A top view of a double-hull, double-bottom, double-longitudinal bulkhead hull after the addition of isolated empty compartments;

[0029] Figure 4 for Figure 3 A schematic diagram of the AA perspective;

[0030] Figure 5 This is a top view of the optimized double-hull, double-bottom, double-longitudinal bulkhead hull design.

[0031] Figure 6 This is a cross-sectional view of the optimized double-hull, double-bottom, double-longitudinal bulkhead hull type;

[0032] Among them, 1-middle cargo hold, 2-side cargo hold, 3-ballast water tank, 4-longitudinal bulkhead, 5-transverse bulkhead, 7-methanol tank, 8-inner shell outer plate, 9-forward isolation compartment, 10-rear isolation compartment, 201-first transverse bulkhead, 202-second transverse bulkhead, 204-trough-shaped bulkhead, 206-upper bulkhead block, 207-lower bulkhead block. Detailed Implementation

[0033] The invention will be further described with reference to the accompanying drawings.

[0034] A method for expanding the capacity of a methanol tank, such as Figure 5 , 6 As shown, a first transverse bulkhead 201, identical to the original transverse bulkhead 5, is added to the ship. The longitudinal ribs on the first transverse bulkhead 201 face the side of the transverse bulkhead 5. Between the two inner shells 8, two second transverse bulkheads are installed between the transverse bulkhead and the first transverse bulkhead, extending to the outer plating of the inner shell. The distance between the first and second transverse bulkheads, and the distance between the two transverse bulkheads themselves, is A1. Longitudinal ribs are installed on the second transverse bulkhead 202, with their directions facing the first transverse bulkhead 201 and the transverse bulkhead 5, respectively. One second transverse bulkhead, together with the transverse bulkhead and the outer plating of the inner shell, forms a forward isolation compartment, while the other second transverse bulkhead, together with the first transverse bulkhead and the outer plating of the inner shell, forms a rear isolation compartment. The spacing between the isolation compartments is set between 1200 and 2000 mm, and the minimum distance between two opposing longitudinal ribs is 700 mm. In the optimized design, methanol tank 7 is arranged along the ship's width. Ballast tank 3, along with forward and aft isolation tanks 9 and 10, serves as an isolation compartment when methanol is loaded. Two channel-shaped bulkheads 204 are installed in methanol tank 7, dividing it into three compartments. The length of the methanol tank is A1. When A1 < 16m, a horizontal channel is selected; when L1 ≥ 16m, a vertical channel is selected. If a horizontal channel is used, the upper and lower bulkheads can be placed between the forward and aft isolation compartments. If a vertical channel is used, it needs to be installed inside the tank.

[0035] Set the lower wall pier of the corrugated bulkhead. Usually, the height of the lower wall pier of the corrugated bulkhead can be set to be the same as the highest point of the internal fold angle in the cabin, and the height does not exceed one-third of the height of the corrugated bulkhead. There should be no cross intersection points between the methanol tank and the isolation void space. Therefore, the inclined plate of the lower wall pier needs to have a distance M from the longitudinal girder at the bottom of the tank, and 300 < M < 1000 mm. It is preferably equal to the distance from the bottom longitudinal stiffeners. The lower wall pier of the horizontal tank is generally set in the isolation tank of the methanol tank and can be set according to the size of the isolation tank.

[0036] Set the upper wall pier of the corrugated bulkhead. Usually, the height of the upper wall pier of the corrugated bulkhead is less than the height of the lower wall pier, and the height does not exceed one-fourth of the height of the corrugated bulkhead. The upper wall pier of the horizontal tank is generally set in the isolation tank of the methanol tank and can be set according to the size of the isolation tank.

[0037] The corrugated bulkhead is provided with an upper wall pier 206 and a lower wall pier 207. In this scheme, the corrugated bulkhead 204 can set the methanol tank 7 into 3 tanks along the ship width direction, which is more flexible for loading. At the same time, it can also prevent the influence on the use of methanol fuel when there is an ineffective situation during the use of the methanol tank.

[0038] At the same time, the ballast tank in this scheme can be used as an isolation void space, and a pair of isolation void spaces along the ship length direction can be cancelled and can be used flexibly.

[0039] Principle for setting the corrugated bulkhead: The distance between the intersection points of the inner shell outer plate 8 and the deck is D. When 0 < D < 30 m, one longitudinal dividing bulkhead is set. When 0 < D < 60 m, two longitudinal dividing bulkheads are set. The maximum number does not exceed three longitudinal dividing bulkheads.

[0040] Preferably, the corrugated bulkhead can set the methanol tank as a clean tank, that is, there are no components in the tank, and the liquid residue in the tank can be controlled within 750 ml when cleaning the fuel in the tank.

[0041] Under the same methanol tank volume requirement, the volume loss of the longitudinally distributed methanol tank is:

[0042] H1 = M * (N1 + N2) * (P1 + P2);

[0043] The volume of the methanol tank is: C1 = (M - 2 * B) * (P1 + P2 - C) * (N1 + N2 - 2 * A).

[0044] Under the same methanol tank volume requirement, the volume loss of the transversely distributed methanol tank is:

[0045] H2 = N1 * (M * (P1 + P2) + 2 * M1 * (P1 + P2) - (M1 - M2) * P2));

[0046] C2 = (M + 2 * M1) * (P1 + P2) * (N1 - 2 * A) - (M1 - M2) * P2 * (N1 - 2 * A);

[0047] ΔH=(M*N2-N1*M1)*P1+(M*N2-N1*M2)*P2>0;

[0048] Where: M>M1>M2, P1>P2.

[0049] In other words, under the same capacity requirements for methanol tanks, the transverse layout scheme results in less loss of cargo tank capacity.

[0050] Here is an example:

[0051] Taking a certain VLCC as an example:

[0052] M1=15.18m, M=23.8m, P1=21.6m, P2=5.6m, M2=9.35m, N1+N2=54.135m.

[0053] A = B = C = 1.5m.

[0054] The lost volume of the methanol tank arranged longitudinally is: H1 = 23.8 * 54.135 * 27.2 = 35045 m3.

[0055] The methanol tank volume is: C1 = 27335 m³ 3 .

[0056] We can calculate that N1 = 22m and N2 = 32.135.

[0057] ΔH=12435m 3 .

[0058] This invention allows the methanol tank to be divided into multiple compartments by setting a trough-shaped bulkhead in the cargo hold area. The interior of each compartment is a clean compartment (without any components), which facilitates cargo tank cleaning. After cleaning, other traditional fuels (fuel oil or diesel), oily liquids, or chemical liquids can be loaded, which has strong versatility and flexibility.

[0059] Maintaining the continuity of longitudinal components, the ballast water tank can also be used as an isolation empty tank. When the methanol tank is not used as a methanol tank, the ballast water tank can be used normally.

[0060] This design method can expand upon conventional design methods, minimizing the occupancy of cargo hold space while maintaining the same methanol tank loading capacity.

Claims

1. A method for expanding a methanol tank, wherein the hull has a double-layered outer shell and a double-layered bottom plate, and the interior of the hull is provided with transverse bulkheads (5) and longitudinal bulkheads (4), the transverse bulkheads and longitudinal bulkheads enclosing a cargo hold area, and the cargo hold area is provided with a central cargo hold (1), a side cargo hold (2), and a ballast water tank (3) arranged sequentially from the center of the hull to the side, characterized in that, A methanol fuel tank is arranged in the ship width direction, and the specific arrangement method is as follows: A first transverse bulkhead (201) is added between two transverse bulkheads (5). Both ends of the first transverse bulkhead pass through the inner hull outer plate (8) of the ship and extend to the outermost hull outer plate. The first transverse bulkhead is parallel to the transverse bulkhead. Two second transverse bulkheads (202) are arranged between the transverse bulkhead (5) and the first transverse bulkhead (201). Both ends of the second transverse bulkhead extend to the inner hull outer plate of the ship. One of the second transverse bulkheads and the transverse bulkhead and the inner hull outer plate form a front isolation tank (9), and the other second transverse bulkhead and the first transverse bulkhead and the inner hull outer plate form a rear isolation tank (10). The two second transverse bulkheads and the inner hull outer plate of the ship form a methanol fuel tank (7), and the ballast water tanks (3) on both sides are used as lateral isolation empty tanks for the methanol fuel tank. Corrugated bulkheads are arranged in the methanol fuel tank. The distance between the intersections of the inner shells on both sides of the methanol fuel tank and the deck is D. When 0 < D < 20m, the number of longitudinally divided corrugated bulkheads (204) is 0; when 20 < D < 30m, the number of longitudinally divided corrugated bulkheads is 1; when 30 ≤ D < 60m, the number of longitudinally divided corrugated bulkheads is two, and the number of corrugated bulkheads does not exceed ②. The length of the methanol tank separated by the corrugated bulkhead is L1. When L1 < 16m, the corrugated bulkhead is set as a horizontal groove; when the length of the methanol tank L1 ≥ 16m, the corrugated bulkhead is set as a vertical groove. The corrugated bulkhead has an upper wall pier (206) and a lower wall pier (207). In the case of a vertical groove, the height of the lower wall pier is consistent with the highest point of the inner fold of the tank, and the height does not exceed one-third of the height of the corrugated bulkhead. There is a distance M between the inclined plate of the lower wall pier and the longitudinal girder at the bottom of the tank, 300 < M < 1000mm, or M is equal to the distance between the bottom longitudinal members. Longitudinal members are arranged on the transverse bulkhead, the first transverse bulkhead, and the two second transverse bulkheads, and the longitudinal members are all located in the front isolation empty tank and the rear isolation empty tank. In the case of a vertical groove, the height of the upper wall pier is less than the height of the lower wall pier, and the height of the upper wall pier does not exceed one-fourth of the height of the corrugated bulkhead.

2. A method for expanding a methanol tank according to claim 1, characterized in that, The internal distance between the front isolation empty tank and the rear isolation empty tank is 1200 - 2000mm.

3. A method for expanding a methanol tank according to claim 1, characterized in that, In the case of a horizontal groove, the upper wall pier and the lower wall pier are respectively arranged in the isolation tanks in front of and behind the methanol fuel tank.

4. A method for expanding a methanol tank according to claim 1 or 3, characterized in that, The number of longitudinally divided corrugated bulkheads arranged in the methanol fuel tank does not exceed 3.

5. A method for expanding a methanol tank according to claim 1, characterized in that, 6. A method for expanding a methanol tank according to claim 1, characterized in that, One longitudinally divided corrugated bulkhead divides the methanol fuel tank into two methanol tanks. The bulkheads of the front isolation empty tank and the rear isolation empty tank have longitudinally aligned members, and the minimum distance between the aligned longitudinal members is 700mm.

Images