A dual-fuel container ship oil tank also serving as a methanol tank

Abstract

The application discloses a kind of dual-fuel power container ship oil tank and do methanol tank arrangement scheme, solve the problem of insufficient fuel tank capacity or excessive occupation of cargo space of dual-fuel ship, and alleviate the problem of waste of methanol tank space when methanol supply is insufficient.The scheme, fuel tank is arranged below the living area, or an additional adjacent 40 feet BAY box position is occupied, methanol tank is arranged in the middle of the ship, and oil tank is arranged on both sides and separated from the methanol tank by isolation air tank, the cabin is separated from the cargo tank and ballast tank by isolation air tank, and the cabin is turned outward to the surrounding isolation air tank to ensure the convenience of future special coating.The application not only ensures the endurance of fuel mode when the initial methanol supply is insufficient, but also satisfies the modification of fuel tank in time after the methanol supply chain is improved, and meets the demand of methanol fuel tank capacity.

Description

Technical Field

[0001] The present invention belongs to the field of ship cabin layout, in particular to the technology of oil tanks serving as other fuel tanks. Specifically, it relates to a layout scheme of the oil tank of a dual-fuel container ship serving as a methanol tank, which solves the problem of insufficient fuel tank capacity or excessive cargo hold space occupation in dual-fuel ships. Background Art

[0002] The 72nd MEPC meeting adopted a preliminary strategy for greenhouse gas emissions reduction, proposing a 40% reduction in the shipping industry's carbon intensity by 2030 and a 70% reduction by 2050, based on 2008 emissions. The European Commission also implemented the core policies of the "EU Green Deal": starting January 1, 2023, the shipping industry will be officially included in the existing ETS (Emission Trading System). Starting January 1, 2025, the EU will limit the lifecycle greenhouse gas intensity of fuels and impose a tax on fuel sold and used within the European Economic Area. The stringent emission reduction targets and high fuel taxes are forcing shipowners to seek cleaner alternative fuels. So-called "green methanol"—CO2 captured from biofuels or renewable energy, and green hydrogen produced with renewable electricity—can be carbon neutral. Methanol dual-fuel ships are also cheaper to build than LNG dual-fuel ships of the same design because they do not require expensive fuel storage tanks and gas fuel processing systems, and methanol can be stored and transported as a liquid, requiring no cooling or pressurization. This has led some shipowners to consider dual-fuel methanol vessels. However, due to the current lack of methanol fuel refueling infrastructure and an incomplete methanol supply chain, the supply of green methanol is very limited compared to the potential demand for shipping. Therefore, dual-fuel methanol vessels will likely continue to use fuel oil in the initial stages of operation. This requires not only sufficient methanol tank capacity but also sufficient fuel tank capacity to ensure a certain range when methanol supply is insufficient. This demand will, to a certain extent, affect cargo capacity and design changes. Therefore, considering the fuel tank also serving as a methanol tank can reduce the loss of cargo hold volume to a certain extent, ensuring sufficient methanol tank capacity in the future while flexibly addressing the current reality of insufficient methanol supply. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a layout scheme for the oil tank of a dual-fuel container ship also serving as a methanol tank, so as to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A dual-fuel container ship oil tank also serves as a methanol tank layout (two layout cases), including a methanol fuel tank arranged amidships, a fuel oil tank arranged on the side of the ship, and an isolated void tank set up in accordance with the requirements of the regulations.

[0006] Layout plan CASE1 includes two fuel tanks and one methanol tank. Its layout is: one methanol tank and two fuel tanks are arranged in the ship's width direction, and one methanol tank and one fuel tank are arranged in the ship's length direction. The two fuel tanks are arranged on both sides of the hull, and the methanol tank is arranged in the ship. The fuel tanks and methanol tanks are separated by cofferdams. All fuel tanks are separated from other surrounding areas (including cargo holds, ballast tanks and TCS, etc.) by cofferdams.

[0007] Layout plan CASE2 includes four fuel tanks and two methanol tanks. Two methanol tanks and two fuel tanks are arranged in the ship's width direction, and one methanol tank and two fuel tanks are arranged in the ship's length direction. The fuel tanks are arranged on both sides of the hull, and the methanol tank is arranged amidships. The fuel tanks and methanol tanks are separated by cofferdams. A horizontal corrugated bulkhead is designed between the two fuel tanks in the ship's length direction for separation, and a vertical corrugated bulkhead is arranged between the two methanol tanks. Top and bottom piers are designed at the top and bottom of the corrugated bulkheads for structural stress bearing. All fuel tanks are separated from other surrounding areas (including cargo holds, ballast tanks and TCS, etc.) by cofferdams.

[0008] Preferably, the fuel tank capacity should be strictly controlled to not exceed 2,500m 3 After determining the required capacity of the fuel tank and methanol tank, the tanks are divided. Due to the different endurance requirements of different shipowners and different routes, the layout of the fuel tanks varies, so the specific number of compartments depends on the actual situation.

[0009] Preferably, if the fuel tank needs to be divided in the longitudinal direction, such as CASE2, a horizontal grooved bulkhead is used between the two fuel tanks in the longitudinal direction, which only bears the pressure of the fuel tank bulkhead and the pressure of the fuel. If it needs to be converted into a methanol tank in the future, the bulkhead can be opened up without affecting the stress condition of the entire fuel tank.

[0010] Preferably, the fuel tank has a small capacity and needs to be divided into compartments, and is preferably arranged on the side of the ship, and arranged in sequence from both sides of the ship to the middle of the ship to reduce the ship's roll. Whether the methanol tank in the ship needs to be divided again is determined according to the structural stress and the size of the tank capacity.

[0011] Preferably, the fuel tank and other compartments, such as the cargo hold, ballast tank, etc., are all arranged with isolated air tanks. Methanol is flammable, explosive and toxic. In order to prevent methanol from leaking to other compartments, an isolated air tank of a certain width needs to be set around it.

[0012] Preferably, the fuel tank layout allows for the simultaneous loading of both fuel oil and methanol, with an isolation void space between the fuel and methanol tanks. In the mid-term, when methanol supply increases but cannot fully meet shipping market demand, the simultaneous loading of fuel oil and some methanol is considered. Methanol is a flammable and explosive fuel with a low flashpoint. To prevent leaks between fuel tanks, which could cause fires or cross-contamination, an isolation void space is required between the fuel and methanol tanks.

[0013] Preferably, the isolation tank not only serves to isolate the two fuel compartments, but also, since methanol is corrosive to a certain extent, the inner wall of the methanol compartment needs to be specially coated. In order to ensure the smoothness of the inner wall of the fuel compartment and facilitate the special coating work in the future, it is considered to turn the structural strips outward into the isolation tank to meet the structural stress of the fuel compartment.

[0014] The isolation chamber should ideally undergo routine maintenance and overhaul. Its width and height should not only accommodate the layout of the strips but also allow for easy access. Furthermore, to prevent leakage of methanol liquid or vapor, the isolation chamber should be adequately ventilated, with ventilation ducts located within the platforms under the lashing bridges on the front and rear walls of the residential area.

[0015] Preferably, if the methanol tank is divided again, such as CASE2, in order to ensure the tank capacity, no isolation compartment is set between the methanol tanks, and the structural strips cannot be placed. Therefore, it is considered to use a vertical grooved bulkhead between the two methanol tanks, and design top and bottom piers to increase the structural stress, meet the structural strength requirements, and reduce the difficulty of special coating construction.

[0016] Preferably, when the fuel tank is converted into a methanol tank, it needs to be specially coated first. If the fuel tank is only arranged under the living area and only one fuel tank is arranged in the direction of the captain, such as CASE1, the tank can be directly cleaned and specially coated to be converted into a methanol tank; if the fuel tank also occupies a 40-foot BAY space in the cargo hold and two fuel tanks are arranged in the direction of the captain, the horizontal grooved bulkhead between the two fuel tanks can be opened first, and the two fuel tanks in the direction of the captain can be merged into one tank, and then the tank can be cleaned and specially coated to reduce the workload of the special coating operation.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention can effectively reduce the loss of cargo hold volume and the change of oil tank layout design by using the fuel tank to serve as a methanol tank. It can concentrate the fuel tank at a certain position on the hull, simplify the design of the filling pipeline, and facilitate the operation of the shipowner. This layout scheme is flexible in application and can meet the tank capacity requirements of three navigation cases: loading only fuel, loading fuel and methanol at the same time, and loading only methanol during the design stage. The fuel tanks on both sides can be selectively modified or gradually modified according to the changes in the methanol supply. The capacity of each fuel tank can be flexibly changed while meeting the endurance requirements, and the problem of insufficient methanol supply can be addressed with minimal tank capacity loss. In addition, when arranging the isolated empty tank according to the specifications, this scheme takes into account the structural stress requirements of the fuel tank and the construction difficulty of the special coating operation in the future. It adopts the method of turning outward strips, separating grooved bulkheads and combining top pier / bottom pier stress to ensure the smoothness of the inner wall of the fuel tank and maximize the utilization of the isolated empty tank space while meeting the structural strength requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic cross-section of a fuel tank also serving as a methanol tank solution (CASE 1) of the present invention;

[0020] Figure 2 1. It is a longitudinal cross-sectional schematic diagram of a fuel tank also serving as a methanol tank solution (CASE 1) of the present invention;

[0021] Figure 3 This is a cross-sectional schematic diagram of a solution (CASE 2) of the present invention in which a fuel tank also serves as a methanol tank;

[0022] Figure 4 It is a schematic longitudinal section of the fuel tank also serving as a methanol tank solution (CASE2) of the present invention. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. This embodiment does not constitute a limitation to the present invention.

[0024] The specific implementation of the CASE1 arrangement is as follows:

[0025] like Figure 1 and Figure 2 As shown, a layout scheme for a dual-fuel container ship oil tank that also serves as a methanol tank includes a cofferdam 1 for dividing the fuel tank from other compartments, methanol tanks 1-2, fuel oil tanks 1-3 (P&S), an isolation void tank 4 between the methanol tank and the fuel oil tank, a side ballast tank 7, and a double bottom ballast tank 8.

[0026] The methanol tank 1-2 and fuel tank 1-3 (P&S) are arranged below the living area. The methanol tank 1-2 is arranged in the ship, and the fuel tank 1-3 (P&S) is arranged on both sides of the hull. The methanol tank 1-2 and the fuel tank 1-3 (P&S) are separated by an isolation tank 4 respectively, and all fuel tanks are separated from other compartments by an isolation tank 1.

[0027] According to the SOLAS regulations, the capacity of a single fuel tank shall not exceed 2500m 3 Therefore, the fuel tanks 1-3 (P&S) have a smaller capacity and are arranged on both sides of the hull, while the methanol tanks 1-2 have a larger capacity and are arranged in the middle of the ship.

[0028] The fuel tank and other compartments must be separated by an isolated void space 1. According to the regulations, there must be an isolated void space between the methanol tank and the ballast tank and cargo hold. If the fuel tank is used as a methanol tank in the future, this requirement must also be met.

[0029] In the mid-term stage when the supply of methanol increases but cannot fully meet the demand of the shipping market, the fuel tank is considered to be loaded with fuel oil and some methanol at the same time. Methanol is a low-flash point fuel and is flammable and explosive. In order to prevent leakage between fuel tanks causing fire or mutual contamination, an isolation tank 4 needs to be arranged between the fuel tank and the methanol tank.

[0030] A distance of approximately 8.5m-9.5m is reserved between the top of the cofferdam 1 and the upper deck for arranging the sewage treatment room and TCS; the height of the cofferdam 1 at the bottom of the fuel tank and the bottom ballast tank is approximately 2 / 3 to 1 box height, which meets the passage requirements; the width of the cofferdam 1 at the fuel tank and the side ballast tank or cargo hold is approximately 1.5m-2.0m, which meets the passage and structural layout requirements.

[0031] The cofferdam 4 is approximately 2.0-2.5 meters across the ship's width, and its length and depth are consistent with the fuel tanks. Methanol is corrosive, requiring a special coating on the interior walls of the methanol tank. To ensure smoothness and facilitate future coating, the design incorporates the structural strips into the cofferdam 4&1 to support the fuel tank's structural loads.

[0032] Even after the structural bars are turned outward, the cofferdams 1 and 4 must still meet basic access requirements. Inspection and maintenance of the bilge require access through the cofferdams. Cofferdams 1 and 4 must be designed with safe passageways for personnel access and rescue, allowing injured personnel to be safely evacuated from the cofferdam bottom. Platforms at varying heights must be provided within the cofferdams to ensure long-distance access. Straight or inclined ladders should be designed between the platforms for up and down access. Cofferdams 1 and 4 must be interconnected to ensure that maintenance personnel can quickly rescue anyone in danger from either location.

[0033] When the fuel tanks 1-3 (P&S) are modified, they need to be cleaned first and then specially painted.

[0034] The specific implementation of the CASE2 arrangement is as follows:

[0035] like Figure 3 and Figure 4 As shown, a layout scheme for an oil tank of a dual-fuel container ship that also serves as a methanol tank includes a cofferdam 1 for dividing the fuel tank from other compartments, a methanol tank 2-2 (P&S), a fuel tank 2-3 (including: a bow fuel tank 2-3.1 (P&S) and a stern fuel tank 2-3.2 (P&S)), an isolation void space 4 between the methanol tank and the fuel tank, a top pier 5, a bottom pier 6, a side ballast tank 7, a double bottom ballast tank 8, a horizontal corrugated bulkhead 9 between the fuel tanks (2-3.1 & 2-3.2), and a vertical corrugated bulkhead 10 between the top pier 5 and the bottom pier 6.

[0036] The methanol tank 2-2 and fuel tank 2-3 are located below the living quarters and occupy a 40-foot bay of cargo space aft. They are symmetrically arranged amidships, with the methanol tank 2-2 located midship and the fuel tank 2-3 located to the side. The fuel tanks are supported by top piers 5, bottom piers 6, and the vertical corrugated bulkheads 10 between them.

[0037] According to the SOLAS regulations, the capacity of a single fuel tank shall not exceed 2500m 3 After occupying a 40-foot bay aft, the fuel tank compartment would be too narrow if arranged according to Case 1, making construction inconvenient and future modifications and cleaning difficult. Therefore, Case 2 opted for a further division of the fuel tank along the length of the ship, dividing it into the fore fuel tank 2-3.1 (P&S) and the aft fuel tank 2-3.2 (P&S).

[0038] Unlike Case 1, the methanol tank 2-2 described in Case 2 is divided into two compartments, the P-side and the S-side. If arranged according to the method in Case 1, the methanol tank capacity amidships would be too large, resulting in a significant impact on the free liquid surface during navigation. Furthermore, the larger capacity of the methanol tank in Case 2 allows for the shipowner to refuel at multiple points throughout the voyage, and considering the differences in methanol content at different ports, different compartments can reduce the mixing of different methanol qualities.

[0039] The methanol tank 2-2 (P&S) is stressed by designing the bulkhead between the top pier 5 and the bottom pier 6 as a vertical groove-type bulkhead, and the top pier 5 and the bottom pier 6 are designed to increase the structural strength, facilitate special coating operations and do not affect the capacity of the methanol tank.

[0040] The fuel tank and other compartments must be separated by an isolated void space 1. According to the regulations, there must be an isolated void space between the methanol tank and the ballast tank and cargo hold. If the fuel tank is used as a methanol tank in the future, this requirement must also be met.

[0041] In the mid-term stage when the supply of methanol increases but cannot fully meet the demand of the shipping market, the fuel tank is considered to be loaded with fuel oil and some methanol at the same time. Methanol is a low-flash point fuel and is flammable and explosive. In order to prevent leakage between fuel tanks causing fire or mutual contamination, an isolation tank 4 needs to be arranged between the fuel tank and the methanol tank.

[0042] Unlike CASE 1, the distance between the top of the cofferdam 1 and the upper deck in CASE 2 is approximately 4.0m-4.5m, and only the TCS can be arranged. The sewage treatment room is moved to other areas to ensure the maximum capacity of the fuel tank; the height of the cofferdam 1 located at the bottom of the fuel tank and the bottom ballast tank is about 2 / 3 to 1 box height, which meets the passage requirements; the width of the cofferdam 1 located between the fuel tank and the side ballast tank or cargo hold is about 1.5m-2.0m, which meets the passage and structural layout requirements.

[0043] The cofferdam 4 is approximately 2.0-2.5 meters across the ship's width, and its length and depth are consistent with the fuel tanks. Methanol is corrosive, requiring a special coating on the interior walls of the methanol tank. To ensure smoothness and facilitate future coating, the design incorporates the structural strips into the cofferdam 4&1 to support the fuel tank's structural loads.

[0044] Even after the structural bars are turned outward, the cofferdams 1 and 4 must still meet basic access requirements. Inspection and maintenance of the bilge require access through the cofferdams. Cofferdams 1 and 4 must be designed with safe passageways for personnel access and rescue, allowing injured personnel to be safely evacuated from the cofferdam bottom. Platforms at varying heights must be provided within the cofferdams to ensure long-distance access. Straight or inclined ladders should be designed between the platforms for up and down access. Cofferdams 1 and 4 must be interconnected to ensure that maintenance personnel can quickly rescue anyone in danger from either location.

[0045] The horizontal corrugated transverse bulkhead 9 between the fuel tanks (2-3.1 & 2-3.2) is designed as a horizontal corrugated bulkhead. It only bears the pressure of the fuel tank bulkhead and the fuel pressure, without affecting the structural stress of the entire fuel tank. When the fuel tank is converted into a methanol tank, the horizontal corrugated transverse bulkhead 9 can be opened to connect the two fuel tanks (2-3.1 & 2-3.2). After opening, the two fuel tanks are combined into a single fuel tank, reducing the difficulty of subsequent modifications (tank cleaning / special coating).

[0046] The layout of the oil tank that also serves as a methanol tank takes into account the actual situation of the shipowner during operation and provides three navigation cases: loading only fuel oil, loading both fuel oil and methanol, and loading only methanol. In the early stages of operation, the supply of methanol is extremely small and the price is high, so only fuel oil navigation is considered; as the methanol supply chain improves and methanol production increases, the price of methanol (unit energy) should still be higher than the price of fuel oil. Shipowners can choose to load both fuel oil and methanol at the same time, using methanol fuel in areas with higher fuel taxes and still using fuel oil in other navigation areas; as methanol fuel becomes more popular, shipowners can choose to first modify one side of the fuel tank to increase the methanol tank's cruising range while still retaining some fuel oil cruising range; when methanol fuel is fully popularized, shipowners can make a final modification to the remaining fuel tank and use methanol fuel exclusively for navigation.

[0047] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for arranging a dual-fuel container ship oil tank that also serves as a methanol tank, characterized by: The fuel tank is located below the living area and occupies an additional 40-foot bay. The methanol tank is located amidships, and the fuel tanks are located on both sides. Isolation void spaces are installed between the fuel tanks and other layout areas in accordance with regulatory requirements. The fuel tanks are four fuel oil tanks and two methanol tanks, which are arranged as follows: two methanol tanks and two fuel oil tanks are arranged in the ship width direction; one methanol tank and two fuel oil tanks are arranged in the ship length direction; The fuel tank capacity is less than 2500m³. The fuel tank can also be used as a methanol tank in the future and meet the applicable specifications for methanol tanks. When the fuel tank is used as a methanol tank, the horizontal grooved bulkhead is opened up and the two longitudinally distributed fuel tanks are converted into one methanol tank, which reduces the special coating area and saves costs. The methanol tank and fuel tank must be separated by an isolation space; The methanol tank and fuel tank are separated from the side ballast tank and bottom ballast tank by an isolation void tank; The methanol tank needs special coating. If the fuel tank also serves as a methanol tank, the fuel tank will also need special coating in the future. Therefore, the fuel tank strip structure is turned outward to the surrounding isolation tank. In order to ensure the convenience of special coating, the middle bulkheads of the two methanol tanks use vertical groove bulkheads for structural stress, and a top pier and bottom pier stress mode is designed.

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