Vessel for transporting a cold fluid, transfer system for a cold liquid product, and method for loading or offloading the vessel

Abstract

The present invention relates to a vessel (3) for transporting a cold fluid, the vessel (3, 70) comprising: a load-bearing structure including a hull extending in a longitudinal direction and at least one transverse cofferdam (9) subdividing the hull into a plurality of segments, the one or each transverse cofferdam (9) including a pair of transverse bulkheads (7, 8) defining an interior space of the transverse cofferdam (9) and an upper wall enclosing the interior space; at least one sealed and thermally insulated compartment (4) disposed in a segment of the hull adjacent to the transverse cofferdam (9); and a gas management device for managing a gas atmosphere in the interior space of the transverse cofferdam (9).

Description

Technical Field

[0001] This invention relates to the field of ships used for transporting a cold fluid. Specifically, this invention relates to the field of ships including sealed and thermally insulated compartments for transporting a liquefied gas (specifically LNG), and liquefied gas-powered ships (e.g., LNG-powered). Prior Technology

[0002] Liquefied natural gas is stored in a sealed and thermally insulated chamber in a one- or two-phase vapor-liquid equilibrium state at low temperatures. Specifically, liquefied natural gas (LNG) is stored at atmospheric pressure at approximately -162°C.

[0003] Various technologies can be used to produce the tank, specifically in the form of an integrated membrane cargo tank or a self-sustaining tank. The thermally insulated barriers of the LNG storage tank and adjacent compartments are a source of heat flow that tends to heat the tank contents, leading to LNG evaporation. Gas derived from natural evaporation is typically used to feed a gas-consuming component to fully utilize the gas. Thus, on an LNG tanker, evaporated gas is used to drive the propulsion unit to propel the ship. However, while this practice allows for optimization of the gas derived from natural evaporation in the LNG transport tank, it does not allow for a reduction in its quantity.

[0004] Furthermore, the intended cargo is LNG contained in the hold that is not consumed by the ship. Therefore, the evaporation rate of the liquid contained in the hold (commonly referred to as the "boil-off rate" (BOR)) is a major issue, specifically leading to the loss of some cargo.

[0005] Several solutions are known for reducing BOR or for recirculating gases evaporated in a LNG tank, specifically: A reliquefaction device via a heat exchanger is used to condense gases originating from natural evaporation; Increase the thickness of the insulation in the cabin; or Use materials with higher thermal efficiency. However, these solutions are reaching a saturation point and no longer allow for a favorable cost-performance ratio. Furthermore, modifying one of the LNG receiving compartments is both complex and expensive.

[0006] Liquefied natural gas (LNG) is also frequently placed on board to supplement fuel or at least one of the fuels used to propel all types of ships, such as LNG carriers or LNG tankers, oil tankers, and container ships. This is referred to as an "LNG-fueled ship" or LFS. In such ships, at least one LNG tank is typically located near a heat source (e.g., an engine room). Summary of the Invention

[0007] One underlying concept of this invention is to provide a vessel that can reduce the temperature within the interior space of a transverse cofferdam to decrease heat flow between this interior space and an adjacent compartment, thereby reducing the evaporation rate in that compartment containing cold liquid. One objective is to reduce the BOR by, for example, 5% or 6%.

[0008] One of the underlying concepts of this invention is to reduce the heat flow (specifically ballast water and atmosphere) between any hollow space of the ship adjacent to the LNG storage tank and the external environment, in order to (for example) reduce the heat flow through the perimeter of such dikes.

[0009] Another concept behind this invention is to reduce the heat flow in the dikes located between a heat source and an LNG tank in order to protect the heat source and the LNG tank from temperature changes.

[0010] Another concept behind this invention is the management of the gas atmosphere within the dikes of a ship.

[0011] Another concept behind this invention is to reduce the temperature in the dikes to reduce the BOR in the LNG storage tanks.

[0012] Another concept behind this invention is to achieve an equilibrium temperature (e.g., -15°C or -25°C) in such cofferdams while maintaining their integrity.

[0013] The decrease in temperature in the hollow spaces of the vessel, and specifically in the cofferdams, poses a risk of frost formation in the interior spaces of the cofferdams (specifically, on the walls or in the insulation). This risk is particularly attributable to the humidity of the surrounding atmosphere. This frost formation involves the risk of degrading the thermal performance of the insulation and the risk of corroding the walls of the cofferdam.

[0014] Therefore, the present invention proposes to solve the described technical problem by integrating a gas management device to manage a gas atmosphere in a hollow space (such as a cofferdam) of the ship.

[0015] definition:

[0016] The term "fluid" includes both liquids and gases.

[0017] The terms "cold" or "low temperature" are defined as a low temperature, such as a negative temperature (in °C), such as -50°C or -162°C.

[0018] The term "cofferdam" is defined as a hollow, separate space in a vessel adjacent to at least one of the compartments; it may also be referred to as a "caisson" or "dry grid".

[0019] The term "valve" refers to a valve or a gate valve.

[0020] According to one embodiment, the present invention provides a vessel for transporting a cold fluid, the vessel comprising: A load-bearing structure includes a hull extending in a longitudinal direction and at least one transverse cofferdam that subdivides the hull into a plurality of segments, the one or each transverse cofferdam including a pair of transverse bulkheads defining an interior space of one of the transverse cofferdams and a superwall enclosing the interior space; At least one sealed and thermally insulated compartment is located in a segment of the hull adjacent to the transverse cofferdam; A gas management device for managing a gas atmosphere in the internal space of the transverse cofferdam, wherein the gas management device includes: A dry air supply line includes a first end located outside the transverse dike and connected to a dry air generator supplying dry air, and a second end located within the interior space of the transverse dike; An intake valve is installed on the dry air supply line; A gas discharge pipeline, comprising a first end located within the interior space of the transverse cofferdam and a second end located outside the vessel; A discharge valve, installed on the gas discharge line, is configured to open when a relative pressure in the internal space rises above a first critical limit. A pressure sensor configured to detect a relative pressure within the interior space of the transverse dike; A pressure regulator connected to the pressure sensor and the intake valve, the pressure regulator being configured to: When the relative pressure in the internal space drops below a second threshold, the intake valve is opened. The second threshold is a positive value that is lower than the first threshold.

[0021] These features allow for the regulation of the gas atmosphere pressure within the interior space of the transverse cofferdam to maintain it above the surrounding pressure, thereby preventing the spontaneous emergence of surrounding air and moisture. These features particularly allow for the prevention of corrosive damage to various components located within the interior space of the transverse cofferdam. Furthermore, the gas management device allows the relative pressure to be maintained within a positive range between the second and first threshold values, regardless of temperature variations within the interior space or variations in surrounding pressure. The first threshold value limits the pressure applied to the transverse bulkheads and the upper wall of the transverse cofferdam.

[0022] According to an embodiment, this vessel may include one or more of the following features.

[0023] According to one embodiment, the pressure regulator is further configured to: When the pressure in the internal space rises above a third threshold value within the range between the second and first threshold values, the intake valve is closed.

[0024] By leveraging these hysteresis characteristics, the operation of the intake valve is optimized and the excessive opening or closing of the intake valve can be avoided, which could lead to premature wear of the equipment.

[0025] According to one embodiment, the difference between the third threshold value and the second threshold value is less than 2 kPa (20 mbarg).

[0026] According to one embodiment, the difference between the third threshold value and the second threshold value is in the range of 0.5 kPa to 1.5 kPa, for example, a difference of 1 kPa.

[0027] According to one embodiment, the pressure regulator is further connected to the discharge valve, and the pressure regulator is further configured to: When the pressure in the internal space rises above the first critical limit, the discharge valve is opened.

[0028] These features facilitate and enable centralized management of the programming and management of the opening and closing parameters of the inlet valve and the outlet valve of the gas management device.

[0029] According to one embodiment, the pressure regulator is further configured to: When the pressure in the internal space drops below a fourth threshold value between the first and second threshold values, the discharge valve is closed.

[0030] By taking advantage of these hysteresis characteristics, the operation of the discharge valve is optimized and the valve is prevented from being opened or closed too many times, which could lead to premature wear of the equipment.

[0031] According to one embodiment, the difference between the fourth threshold value and the first threshold value is less than 2 kPa (20 mbarg).

[0032] According to one embodiment, the difference between the fourth threshold value and the first threshold value is in the range of 0.5 kPa to 1.5 kPa, for example, a difference of 1 kPa.

[0033] According to another embodiment, the discharge valve is a mechanically openable and closeable discharge valve, configured to: It opens when the relative pressure in one of the internal spaces rises above the first critical limit.

[0034] According to one embodiment, the discharge valve is configured to: The dam is closed when the pressure in the internal space of the transverse cofferdam drops below a fourth threshold value between the first and second threshold values.

[0035] According to one embodiment, the discharge valve is selected from a ball valve, a needle valve, a butterfly valve, a gate valve, a check valve, a one-way valve, a piston valve, a diaphragm valve, a high-speed vacuum relief valve, a safety valve, and a spring or tongue safety valve.

[0036] According to one embodiment, the second threshold value is between 1 kPa (10 mbarg) and 10 kPa (100 mbarg), preferably between 2 kPa (20 mbarg) and 5 kPa (50 mbarg).

[0037] According to one embodiment, the second critical limit is 2 kPa or 5 kPa.

[0038] According to one embodiment, the first threshold value is in the range of 12 kPa (120 mbarg) to 18 kPa (180 mbarg), preferably between 13 kPa (130 mbarg) and 15 kPa (150 mbarg).

[0039] According to one embodiment, the first critical limit is 14 kPa (140 mbarg).

[0040] According to one embodiment, the gas management device further includes a gas vent valve installed on the gas discharge line upstream of the vent valve to allow a volume of gas to be drawn from the interior space of the transverse dike.

[0041] With these features, a certain amount of gas can be easily extracted from the internal space of the transverse cofferdam, without having to enter the internal space of the transverse cofferdam or extract a gas sample from the second end of the discharge line, which is not always easily accessible. Furthermore, this allows gas extraction without operating the discharge valve and thus without interrupting its operation.

[0042] According to one embodiment, the transverse bulkheads are manufactured from a steel grade selected from D, E, DH, and EH. Preferably, it is a D or / or E grade steel.

[0043] According to one embodiment, the thickness of the pair of transverse bulkheads is greater than or equal to 10 mm, for example, in the range of 10 mm to 50 mm, preferably in the range of 15 mm to 20 mm.

[0044] According to one embodiment, the longitudinal walls of the cofferdam are manufactured from steel grades selected from D, E, DH, and / or EH. Preferably, it is D or / or E grade steel.

[0045] According to one embodiment, the thickness of the longitudinal walls of the cofferdam is greater than or equal to 10 mm, for example, in the range of 10 mm to 50 mm, preferably in the range of 15 mm to 20 mm.

[0046] The International Gas Code describes the specific characteristics of the indicated steel grade.

[0047] With these features, temperatures below -15°C and / or -25°C can be achieved in the interior space of the transverse cofferdam without damaging the transverse bulkheads.

[0048] According to one embodiment, the transverse cofferdam includes a thermal insulator.

[0049] With these features, the heat flow between the sealed and thermally insulated compartment and the one or more heat sources located near the ship is reduced.

[0050] According to one embodiment, the thermal insulation is located on the outer surface of one of the cofferdams. According to one embodiment, the thermal insulation is located on the outer surface of one of the pair of transverse bulkheads.

[0051] According to one embodiment, the thermal insulation is located in the interior space of the transverse cofferdam, and the thermal insulation is preferably attached to the longitudinal wall of the transverse cofferdam, which includes the upper wall and a portion of the interior hull.

[0052] With these characteristics, the gas management device allows the thermal insulation material to be maintained in a dry state. Therefore, the thermal insulation material is not damaged by moisture or water accumulation. Thus, the thermal properties of the thermal insulation material are optimally maintained.

[0053] According to one embodiment, when the transverse cofferdam is adjacent to a single compartment, the thermal insulation further covers the bulkhead of the pair of bulkheads furthest from that compartment.

[0054] According to one embodiment, the thermal insulation material is a thermally insulating glass wool covered with a thermally insulating metal foil or foam on the outside. Preferably, the thermal insulation material is a thermally insulating glass wool covered with a metal foil (e.g., an aluminum layer). According to one embodiment, the thermally insulating foam is polyurethane foam (PUF).

[0055] According to one embodiment, the density of the thermally insulating glass wool is in the range of 20 kg / m3 to 60 kg / m3, and preferably 22 kg / m3.

[0056] According to one embodiment, the density of the thermal insulation foam is in the range of 20 kg / m3 to 80 kg / m3, preferably 50 kg / m3.

[0057] With these characteristics, heat loss is reduced and thus facilitates the management of the gas atmosphere in the interior space of the transverse dike.

[0058] According to one embodiment, the thickness of the thermally insulating glass wool is between 100 mm and 400 mm, preferably between 200 mm and 350 mm, for example, 200 mm.

[0059] According to one embodiment, the thickness of the thermal insulation foam is between 100 mm and 400 mm, preferably between 200 mm and 350 mm, for example, 200 mm.

[0060] With these features, temperatures below -15°C and / or -25°C can be achieved in the interior space of the transverse cofferdam.

[0061] According to one embodiment, the dry air supply line passes through the upper wall.

[0062] According to one embodiment, the second end of the dry air supply line appears near the bottom wall of one of the transverse cofferdams.

[0063] According to one embodiment, the gas discharge line passes through the upper wall.

[0064] According to one embodiment, the first end of the gas emission line is located near the upper wall.

[0065] With these features, the dry air supplied to the interior space of the transverse dike allows the gas located in the interior space of the transverse dike to be discharged more efficiently via the discharge line.

[0066] According to one embodiment, the dry air supply line and the gas discharge line are made of steel or another material selected from: stainless steel, D grade, E grade, DH grade and / or EH grade steel.

[0067] According to one embodiment, the water content in the internal space of the transverse cofferdam is maintained below 25% (e.g., below 15%) and preferably below 5%. According to one embodiment, the water content in the internal space of the transverse cofferdam is close to 0%.

[0068] Because of these characteristics, the formation of frost on the thermal insulation or on the walls of the cofferdam is limited. Therefore, the risk of degrading the thermal performance of the insulation or corroding the walls of the cofferdam is significantly reduced.

[0069] According to one embodiment, the dry air has a dew point temperature of less than -15°C, preferably less than -20°C, for example, less than or equal to -45°C, or for example, between -20°C and -40°C or between -25°C and -30°C.

[0070] According to one embodiment, the pressure sensor is a piezoresistive pressure sensor for measuring gauge pressure (GP). According to one embodiment, the sensor is made of corrosion-resistant steel resistant to negative temperatures, for example, it is made of SUS316L steel. According to one embodiment, the pressure sensor includes a diaphragm.

[0071] According to one embodiment, the pressure regulator is electronic.

[0072] According to one embodiment, the intake valve and / or the exhaust valve is a solenoid valve.

[0073] According to one embodiment, several intake valves are installed in series on or from the dry air supply line. These intake valves may be different.

[0074] According to one embodiment, several discharge valves are installed in series on or from the gas discharge line. These discharge valves may be different.

[0075] With these features, the ship's gas management equipment is better suited for ships where the gas management equipment is integrated. Furthermore, these features allow for enhanced safety, monitoring, and ease of maintenance of the ship's gas management equipment.

[0076] According to one embodiment, the dry air generator is an appliance that dries the atmosphere by heating.

[0077] According to one embodiment, the dry air generator is an appliance that provides dry air with a dew point temperature of less than -40°C and preferably -45°C.

[0078] According to one embodiment, the dry air generator supplies dry air to the interior space of the transverse dike at a flow rate in the range of 10,000 m3 / h to 20,000 m3 / h (e.g., 15,000 m3 / h) to fill the transverse dike with dry air.

[0079] According to one embodiment, the dry air generator supplies dry air to the interior space of the transverse dike at a flow rate in the range of 50 m3 / h to 500 m3 / h to manage the gaseous atmosphere in the interior space of the transverse dike.

[0080] According to one embodiment, the dry air generator used is one that is already installed on the ship. This reduces costs by eliminating the need to provide a dedicated dry air generator for the gas management equipment to manage the gas atmosphere in the interior space of the transverse dike.

[0081] According to another embodiment, the gas management device for managing a gas atmosphere in the internal space of the transverse cofferdam includes: A dry air supply line includes a first end located outside the transverse dike and connected to a first dry air generator supplying dry air, and a second end located within the interior space of the transverse dike, wherein a first air intake valve is installed on the dry air supply line. The dry air generator is configured to deliver a dry air flow rate greater than 10,000 m³ / h (e.g., between 10,000 m³ / h and 20,000 m³ / h) into the interior space of the cofferdam; A second dry air generator is connected to the dry air supply line branching off from the first dry air generator, wherein a second air inlet valve is installed between the second dry air generator and the dry air supply line, and the second dry air generator is configured to deliver a dry air flow rate of less than 1,000 m3 / h (e.g., between 50 m3 / h and 500 m3 / h) to the interior space of the cofferdam.

[0082] Advantageously, the first dry air generator, the dry air supply line, and the first intake valve are components typically present in an LNG tanker. This embodiment is particularly advantageous because it limits the additional components to be installed on the ship.

[0083] According to one embodiment, the dry air generator is connected to the pressure regulator, and the pressure regulator is further configured to: When the relative pressure in the internal space drops below the second critical value, or in other words, when the intake valve opens, the emission of dry air from the dry air generator to the supply line is initiated.

[0084] According to one embodiment, the present invention also provides a conveying system for a cold liquid product, the system comprising: the aforementioned vessel; insulating pipes configured to connect the compartment installed in the hull of the vessel to a floating or shore-based storage device; and a pump for feeding a flow rate of the cold liquid product from the floating or shore-based storage device to the compartment of the vessel or from the compartment of the vessel to the floating or shore-based storage device through the insulating pipes.

[0085] According to one embodiment, the present invention also provides a method for loading or unloading a vessel, wherein a cold liquid product is routed from a floating or shore-based storage device to the vessel's compartment or from the vessel's compartment to a floating or shore-based storage device via an insulated pipe.

[0086] With these features, the BOR can be reduced by 2% to 6%, and preferably by 5% to 6%.

[0087] Some aspects of the present invention are based on the concept of drying the interior space of the transverse cofferdam to allow for a reduction in the temperature within the interior space of the transverse cofferdam without damaging the vessel.

[0088] A vessel's gas management equipment can be integrated via pipes and valves already present on the vessel (e.g., on an LNG tanker). Additionally, extra management or safety valves can be integrated into the vessel. Simple Explanation of the Diagram

[0089] The invention will be better understood in the following description of certain specific embodiments of the invention, provided only in a non-limiting manner, with reference to the accompanying drawings, and further objectives, details, features, and advantages thereto will become more apparent.

[0090] Figure 1 illustrates a typical temperature variation as a function of time for one of the cofferdams of a liquefied natural gas (LNG) vessel during operation. Figure 1 is not part of the invention but is helpful for understanding.

[0091] Figure 2 is a cross-sectional view along the longitudinal axis of a liquefied natural gas carrier according to one embodiment.

[0092] Figure 3 is a perspective view and cross-sectional view of a transverse cofferdam that can be used in the ship of Figure 2 according to one embodiment.

[0093] Figure 4 is a cross-sectional view of a transverse cofferdam in the ship of Figure 2, which includes a thermal insulator according to one embodiment.

[0094] Figure 5 is a schematic diagram of a transverse cofferdam according to one embodiment, which has a gas management device for managing a gas atmosphere that can be used in the interior space of a transverse cofferdam in the ship of Figure 2.

[0095] Figure 6 is a schematic diagram of a transverse cofferdam according to another embodiment, which has a gas management device for managing a gas atmosphere that can be used in the interior space of a transverse cofferdam in the ship of Figure 2.

[0096] Figure 7 is a cross-sectional schematic diagram of an LNG tanker according to one embodiment, including a compartment and a terminal for loading / unloading the compartment.

[0097] Figure 8 shows a schematic cross-sectional view of one of the oil tankers in the transverse direction.

[0098] Figure 9 is a cross-sectional view of the stern of a ship including a sealed and thermally insulated compartment for storing a liquefied fuel gas, the compartment being located longitudinally aft of the bridge of the ship. Implementation

[0099] Figure 1 shows a graph representing the temperature variation T (°C) of a cofferdam as a function of time (t). Significant temperature variations are common during ship navigation. In fact, when the ship is entirely LNG-supplied, step 1 involves draining seawater from the ship's ballast tanks, and due to the heat flow from the tanks to the cofferdam, the temperature of the cofferdam adjacent to the cryogenic tanks decreases significantly. According to step 2, when the ship unloads or uses LNG, part of the tanks is thus emptied and the ballast tanks are filled with seawater for optimal navigation. Therefore, the temperature of the cofferdam varies via heat transfer from the seawater in the ballast tanks to the cofferdam. Generally, the temperature in the cofferdam increases during step 2. Therefore, by repeating steps 1 and 2, the ship completes the cycle. Thus, it is difficult to regulate the temperature in the cofferdam.

[0100] Figure 2 shows a vessel 3 equipped with a liquefied natural gas storage and transport facility, comprising four sealed and thermally insulated compartments 4. Each compartment 4 is associated with a degassing mast 5 provided on the deck 12 of the vessel 3, which allows vapor phase gas to escape when excessive pressure exists inside the associated compartment 4. An engine room 6 is provided at the stern of the vessel 3, and this compartment typically includes a hybrid power supply steam turbine capable of being operated by burning diesel fuel or by burning vaporized gases originating from the compartment 4. The compartments 4 have a longitudinal dimension extending in the longitudinal direction of the vessel 3. Each compartment 4 is joined at its longitudinal ends by a pair of transverse bulkheads 7, 8 to define a sealed gap space (referred to as a "cofferdam" 9). Thus, the compartments 4 are separated from each other by a transverse cofferdam 9. Thus, each compartment 4 is configured within a load-bearing structure formed on one hand by the double hull of the vessel 3 and on the other hand by one of the transverse bulkheads 7, 8 of the cofferdams 9 joined to the compartment 4.

[0101] Ships according to embodiments of the present invention may include several types of compartments and are not limited to a specific compartment (e.g., a membrane compartment for storing liquefied gases). Ship 4 has a multi-layered structure (not shown) comprising, from the outside to the inside, a primary thermally insulating barrier abutting an insulating element of a supporting structure, a primary sealing membrane abutting the secondary thermally insulating barrier, a primary thermally insulating barrier including an insulating element abutting the secondary sealing membrane, and a primary sealing membrane intended to contact the liquefied gas contained in the compartment. The primary sealing membrane defines an internal space of compartment 4 for receiving liquefied gases.

[0102] The liquefied gas intended to be stored in the tank can specifically be liquefied natural gas (LNG) (i.e., a gaseous mixture mainly consisting of methane and one or more other hydrocarbons). The liquefied gas can also be ethane or liquefied petroleum gas (LPG) which mainly consists of propane and butane (i.e., a mixture of hydrocarbons derived from oil refining).

[0103] Figure 3 shows a cross-sectional and perspective view of a transverse cofferdam 19 in a twin-hull vessel comprising an outer hull 10 and an inner hull 15 according to one embodiment. The transverse cofferdam 19 includes a pair of transverse bulkheads defining an internal space 13 of the transverse cofferdam 19. Only one of the two transverse bulkheads 17 is shown in Figure 3 to illustrate the internal space 13 of the transverse cofferdam 19. The transverse cofferdam 19 further includes an upper wall 37 that encloses the internal space 13. As an example, the upper wall 37 may be a wall parallel to the upper deck 12 of the vessel. A portion of the inner hull 15 opposite the upper wall 37 defines the bottom of the internal space of the transverse cofferdam 19. The vessel further includes a ballast tank 41 located outside the transverse cofferdam 19. The ballast tank 41 is formed by the bottom portion of a space located between the inner hull 15 and the outer hull 10 of the vessel.

[0104] The transverse cofferdam 19 further includes a reinforcing structure 14 that intersects the internal space 13 in a non-sealed manner. The internal space 13 of the transverse cofferdam 19 may contain a heating system 16 for controlling the temperature of the transverse cofferdam 19. The heating device is formed by ethylene glycol or another heating antifreeze through a twisted conduit in which it circulates.

[0105] Figure 4 illustrates an embodiment of a transverse cofferdam 19 that further includes a thermal insulation 40 located within the interior space 23 of the transverse cofferdam. The thermal insulation 40 is attached to the longitudinal wall of the transverse cofferdam 29, which includes a portion of the upper wall 37 and the interior hull 15. If the transverse cofferdam 19 is located between two compartments 4, only the two transverse bulkheads 17 are not covered with the thermal insulation 40.

[0106] Figure 5 illustrates a gas management system for managing a gas atmosphere within the interior space 23 of a transverse cofferdam 29 of a vessel, according to one embodiment. The transverse cofferdam 29 includes a pair of transverse bulkheads 107, 109 defining the interior space 23 of the transverse cofferdam and a superstructure 37 enclosing the interior space. As shown in Figure 4, the transverse cofferdam 29 includes a thermal insulator 40 located within the interior space 23 of the transverse cofferdam, wherein the thermal insulator 40 is attached to a longitudinal wall of the transverse cofferdam 29 comprising the superstructure 37 and a portion of the interior hull 15. The ship's gas management equipment includes: A dry air supply line 30 passes through the upper wall 37 of the transverse cofferdam 29 and includes a first end located outside the transverse cofferdam 29 and connected to one of the dry air generators 31 that supply dry air, and a second end located in the interior space 23 of the transverse cofferdam 29 near a portion of the inner hull 15 located near the bottom of the cofferdam (i.e., opposite the upper wall 37). The ship's gas management equipment further includes: An intake valve 32 is installed on the dry air supply line 30 and located outside the transverse dike 29; A gas discharge pipeline 33 passes through the upper wall 37 and includes a first end located within the interior space 23 of the transverse cofferdam 29 and a second end located outside the ship; A discharge valve 34 is located outside the transverse cofferdam 29 and is installed on the gas discharge pipeline 33; A pressure sensor 35 is configured to detect one of the relative pressures within the interior space 23 of the transverse dike 29; A pressure regulator 36 is located outside the transverse dike 29 and is connected to a pressure sensor 35, an intake valve 32 and an exhaust valve 34.

[0107] In this case, the pressure regulator 36 is configured as follows: When the relative pressure in the internal space 23 drops below the second critical limit, the intake valve 32 is opened. The second critical limit is a positive value, for example, approximately 5 kPa. When the relative pressure in the internal space 23 rises above one of the second threshold values ​​(e.g., approximately 15 kPa), the discharge valve 34 opens. Furthermore, the pressure regulator 36 can be configured to perform one or more of these actions: When the relative pressure in the internal space 23 rises above the first threshold, or when it rises above one of the third thresholds between the second and first thresholds (with a hysteresis), the intake valve 32 is closed; When the relative pressure in the internal space 23 drops below the second critical limit, or when it drops below one of the fourth critical limits between the first and second critical limits (with a hysteresis), the discharge valve 34 is closed. This gas management device can be integrated to (for example) regulate the gas atmosphere of the dikes 9 and 19 shown above.

[0108] Figure 6 illustrates a gas management device according to another embodiment for managing a gas atmosphere in the internal space 23 of the transverse cofferdam 29. As before, pressure regulator 136 is connected to pressure sensor 35 and inlet valve 32. This embodiment differs from Figure 5 in that the exhaust valve 134 is a mechanically openable and closeable exhaust valve 134 that is not connected to pressure regulator 136 and automatically opens and closes according to the pressure present in the internal space 23. The mechanically openable and closeable exhaust valve 134 is configured to open when a relative pressure in the internal space 23 rises above a first threshold value and closes again when it falls below this value (with a hysteresis, depending on the situation). Accordingly, the mechanically openable and closeable exhaust valve 134 includes, for example, a spring-loaded closing mechanism or a wing-plate closing mechanism. This mechanically openable and closeable exhaust valve 134 implements a safety function because it specifically prevents damage that can be caused by excessive pressure in the internal space 23 of the transverse cofferdam 29.

[0109] The gas management device further includes a vent valve 18. The vent valve 18 is installed on the gas discharge line 33 outside the transverse dike 29 and upstream of the mechanically openable and closed discharge valve 134. Therefore, a certain amount of gas can be extracted from the internal space 23 of the transverse dike 29 to analyze the gas atmosphere or temperature of the internal space 23 of the transverse dike 29. Thus, the gaseous atmosphere in the internal space 23 of the transverse dike 29 can be regulated. The embodiments described in the figures are not limited to a specific type of transverse dike; for example, the embodiment described in Figure 6 can be applied to the dike described in one of the foregoing figures.

[0110] The transverse cofferdam 29 includes a thermal insulation 40 on the inner surface of the longitudinal wall of the transverse cofferdam 29 covering the entire perimeter of the interior space 23, comprising the upper wall 37 and the interior hull 15, as shown in FIG5. In the embodiment shown in FIG6, the transverse cofferdam 29 further includes a thermal insulation 140 on the inner surface of the transverse wall 107 located opposite the adjacent vessel 4. In this embodiment, the thermal insulation 40 restricts heat flow with ballast water and surrounding air, and the thermal insulation 140 further restricts heat flow with compartments adjacent to the transverse bulkhead 107, and restricts (for example) heat flow with the engine room 6 or any other heat source having a temperature higher than that of the vessel 4.

[0111] The thermal insulation 40 or 140 may be glass wool covered with a vapor barrier (e.g., a layer of aluminum) on the outside. The glass wool may be attached by protruding studs (not shown) having a first end welded to one end of the wall of the transverse dike 29 and passing through the glass wool. To hold the glass wool in place, a locking member, such as a clip, is added above the glass wool on one second end of the stud.

[0112] Regarding Figures 8 and 9, the above describes an embodiment of the previously described gas management equipment installed in other types of ships.

[0113] For example, in a tanker 80, as shown in a cross-sectional view in Figure 8, the ship 80 includes a sealed and thermally insulated compartment 4 located between two cargo tanks 42 that are filled with a cargo (e.g., oil).

[0114] The oil has a temperature higher than that of the LNG in compartment 4. It may also be heated by a heating device to increase its viscosity and facilitate loading or unloading. For example, it may have a temperature of 60°C.

[0115] Each cargo tank 42 is separated from the sealed and thermally insulated tank 4 by a transverse dike 39. The transverse dike 39 is similar to the transverse dike 29 shown above and includes a thermal insulator on at least one inner surface of the transverse bulkhead, thus limiting heat flow 43 with adjacent compartments (i.e., limiting heat flow between tank 4 and cargo tank 42), specifically by limiting heat transfer from cargo tank 42 to tank 4. In other words, tank 4 is thermally insulated from the oil stored in cargo tank 42 at a temperature higher than that of the liquefied gas stored in tank 4. Similarly, cargo tank 42 is thermally insulated from the LNG in tank 4.

[0116] Similarly, the vessel 90 shown in Figure 9 is an LNG-powered vessel. Vessel 90 can be a container ship or a bulk carrier. A bulk carrier is a vessel designed for transporting solid bulk products. Therefore, in a manner known per se, forward of its bridge 44 in a longitudinal direction X'-X, vessel 90 includes one or more cargo holds 45 for transporting a solid bulk product. The cargo holds 45 are spaced apart in a manner known per se in the longitudinal direction X'-X of vessel 90. It should be noted that only one of these cargo holds 45 is schematically shown in Figure 9, namely the cargo hold 45 closest to the bridge 44. Vessel 90 further includes a sealed and thermally insulated compartment 4 containing LNG intended to supply a propulsion system 46. Compartment 4 is located aft of the bridge 6 in the longitudinal direction X'-X. Compartment 4 is separated from the heat source (i.e., the bridge, propulsion system 46, and cargo hold 45) by a transverse dike 49. The transverse cofferdam 49 specifically includes thermal insulation and gas management equipment as described above. Therefore, as with the aforementioned ship, the heat flow between the heat source and compartment 4 is significantly restricted.

[0117] The aforementioned gas management equipment is capable of implementing a method including one of the following steps: - When the relative pressure inside the cofferdam drops below 5 kPa, dry air is sent to the interior of the transverse cofferdam via a dry air supply pipeline generator, so that the cofferdam only receives dry air and not the humid surrounding air; - When the relative pressure increases to above 14 kPa, the gas is discharged from the interior space of the transverse cofferdam to the exterior space of the transverse cofferdam via the discharge pipeline. Therefore, the temperature inside the cofferdam can be reduced to -15°C or -25°C without damaging the ship. The values ​​shown in the figure can be adjusted according to the desired gas management.

[0118] Referring to Figure 7, a cross-sectional view of an LNG tanker 70 shows a typically prismatic sealed and thermally insulated compartment 71 installed within the ship's twin hulls 72. The walls of compartment 71 include a primary sealing barrier intended to contact the LNG contained within the compartment, a secondary sealing barrier disposed between the primary sealing barrier and the twin hulls 72, and two insulating barriers respectively disposed between the primary sealing barrier and the secondary sealing barrier and between the secondary sealing barrier and the twin hulls 72.

[0119] In one of the ways known per se, the loading / unloading pipe 73, located on the deck above the ship, can be connected by a suitable connector to a marine or harbor terminal for transferring an LNG cargo from or to the hold 71.

[0120] Figure 7 illustrates an example of a marine terminal including a loading / unloading station 75, a subsea pipeline 76, and a shore-based facility 77. The loading / unloading station 75 is a fixed offshore facility including a movable arm 74 and a tower 78 supporting the movable arm 74. The movable arm 74 supports a bundle of insulated flexible tubing 79 that can be connected to a loading / unloading pipe 73. The directional movable arm 74 is adaptable to all types of LNG tanker gauges. A connecting line, not shown in the figure, extends into the tower 78. The loading / unloading station 75 allows LNG tankers 70 to load or unload onto or onto shore-based facilities 77. This facility includes a liquefied gas storage tank 80 and a connecting line 81 connected to the loading / unloading station 75 by the subsea pipeline 76. The subsea pipeline 76 allows liquefied gas to be transported a significant distance (e.g., 5 km) between the loading / unloading station 75 and the shore-based facility 77, allowing the LNG tanker 70 to maintain a significant distance from the coast during loading / unloading operations.

[0121] To generate the pressure required for conveying liquefied gas, pumps are provided on board vessel 70 and / or on shore equipment 77 and / or on loading / unloading station 75.

[0122] Although the invention has been described with reference to several specific embodiments, it is obvious that the invention is by no means limited thereto and that if such embodiments fall within the scope of the invention, they include all technical equivalents of the described manner, and combinations thereof.

[0123] Gas management equipment for managing a gas atmosphere in the interior space of a transverse cofferdam may, for example, further include a branch line having a manual valve across, for example, an intake valve or an exhaust valve, or even an alarm system (PAL, PAH, PALL, PAHH) linked to a pressure sensor, without departing from the scope of the invention.

[0124] Some components (specifically, pressure regulator components) can be manufactured in various forms, either standalone or distributed, using hardware and / or software components. Available hardware components include specific ASICs, FPGAs, or microprocessors. Software components can be written in various programming languages, such as C, C++, Java, or VHDL. This list is not exhaustive.

[0125] The use of the verbs “include” or “contain” and their conjugations does not exclude the presence of elements or steps other than those described in a claim.

[0126] Any reference symbols between parentheses in the scope of the patent application shall not be interpreted as limiting the scope of the patent application.

[0127] 1: Steps 2: Steps 3: Ship 4: Sealed and thermally insulated compartment 5: Degassing mast 6: Engine Room 7: Transverse bulkhead 8: Transverse bulkhead 9: Horizontal cofferdam 10:Exterior hull 12:Upper deck 13: Interior Space 14: Strengthen the structure 15:Inner hull 16: Heating System 17: Transverse bulkhead 18: Relief valve 19: Transverse cofferdam 23: Interior Space 29: Transverse cofferdam 30: Dry air supply line 31: Dry Air Generator 32: Intake valve 33: Gas emission pipeline 34: Drain valve 35: Pressure sensor 36: Pressure Regulator 37:Upper wall 39: Transverse cofferdam 40: Thermal insulation 41: Ballast Tank 42: Liquid Cargo Tank 43: Heat Flow 44: Bridge 45: Cargo hold 46: Propulsion System 49: Transverse cofferdam 70: LNG tanker 71: Sealed and thermally insulated compartment 72: Double hull 73: Loading / Unloading Management System 74: Movable arm 75: Loading and unloading station 76: Submarine Pipelines 77: Shore-based equipment 78: Tower 79: Insulating Flexible Tube 80: Tanker / Ship / Liquefied Gas Storage Tank 81: Connecting pipelines 90: Ship 107: Transverse bulkhead 109: Transverse bulkhead 134: Discharge valve 136: Pressure Regulator 140: Thermal insulation

Claims

1. A vessel (3, 70) for transporting a cold fluid, the vessel (3, 70) comprising: A load-bearing structure comprising a hull (110) extending in a longitudinal direction and at least one transverse cofferdam (9, 19, 29) subdividing the hull into a plurality of segments, the one or more transverse cofferdams (9, 19, 29) comprising a pair of transverse bulkheads (7, 8, 17, 107, 109) defining an interior space (13, 23) of the transverse cofferdam (9, 19, 29) and an upper wall (37) enclosing the interior space (13, 23); at least one sealed and thermally insulated compartment (4, 71) disposed in a segment of the hull (110) adjacent to the transverse cofferdam (9, 19, 29); a gas management device for managing a gas atmosphere in the interior space (13, 23) of the transverse cofferdam (9, 19, 29), wherein the gas management device includes: A dry air supply line (30) includes a first end located outside the transverse cofferdams (9, 19, 29) and connected to a dry air generator (31) supplying dry air, and a second end located in the interior space (13, 23) of the transverse cofferdams (9, 19, 29); an intake valve (32) installed on the dry air supply line (30); a gas discharge line (33) including a first end located in the interior space (13, 23) of the transverse cofferdams (9, 19, 29) and a second end located outside the vessel (3, 70); and a discharge valve (34, 134) installed on the gas discharge line (33), the discharge valve (34, 134) being configured to open when a relative pressure in the interior space (13, 23) rises above a first threshold value; A pressure sensor (35) configured to detect a relative pressure in the interior space (13, 23) of the transverse dike; a pressure regulator (36, 136) connected to the pressure sensor (35) and the air intake valve (32), the pressure regulator (36, 136) configured to: open the air intake valve (32) when the relative pressure in the interior space (13, 23) drops below a second threshold value, the second threshold value being a positive value lower than the first threshold value.

2. The vessel as requested in item 1, wherein the pressure regulator (36, 136) is further configured to: close the intake valve (32) when the pressure in the internal space (13, 23) rises above a third threshold value within the range between the second threshold value and the first threshold value.

3. As in Request 2, wherein the difference between the third threshold and the second threshold is less than 2 kPa (20 mbarg).

4. The vessel of any of claims 1 to 3, wherein the pressure regulator (136) is further connected to the discharge valve (34, 134), and the pressure regulator (136) is further configured to: open the discharge valve (34, 134) when the pressure in the internal space (13, 23) rises above the first threshold value.

5. The vessel as requested in item 4, wherein the pressure regulator (36) is further configured to: close the discharge valve (34) when the pressure in the internal space (13, 23) drops below a fourth threshold value within the range between the first threshold value and the second threshold value.

6. As in claim 5, wherein the difference between the fourth threshold and the first threshold is less than 2 kPa (20 mbarg).

7. The vessel of any of claims 1 to 3, wherein the discharge valve (34, 134) is a mechanically openable and closeable discharge valve (34, 134) configured to open when one of the relative pressures in the internal space (13, 23) rises above the first critical limit.

8. For any of the requests 1 to 3, wherein the second limit value is between 1 kPa (10 mbarg) and 10 kPa (100 mbarg).

9. The vessel for any of the requests 1 to 3, wherein the first limit value is between 12 kPa (120 mbarg) and 18 kPa (180 mbarg).

10. The vessel of any one of claims 1 to 3, wherein the gas management equipment further includes a gas vent valve (18) installed on the gas vent line (33) upstream of the vent valve (34, 134) to allow a volume of gas to be drawn from the interior space (13, 23) of the transverse cofferdam.

11. For any of the requests in items 1 to 3, wherein the pair of transverse bulkheads (7, 8, 17, 107, 109) are made of steel grade selected from D, E, DH and EH.

12. The vessel of any of claims 1 to 3, wherein the transverse cofferdam (9, 19, 29) includes a thermal insulator (40) located in the interior space (13, 23) of the transverse cofferdam.

13. The vessel of any of claims 1 to 3, wherein the transverse cofferdam (9, 19, 29) includes a thermal insulator located on one of the outer surfaces of the cofferdam.

14. The ship of claim 12, wherein the thermal insulation (40) is a thermal insulation glass wool consisting of a metal foil covering an outer surface.

15. A conveying system for a cold liquid product, the system comprising: The vessel (3, 70) of any one of claims 1 to 14; insulating pipes (73, 79, 76, 81) configured to connect the compartment (4, 71) installed in the hull (110) of the vessel to a floating or shore storage facility (77); and a pump for feeding a flow of the cold liquid product from the floating or shore storage facility to the compartment of the vessel or from the compartment of the vessel to the floating or shore storage facility through the insulating pipes.

16. A method for loading or unloading a vessel (3, 70) as claimed in any of claims 1 to 14, wherein a cold liquid product is routed from a floating or shore storage facility (77) to the compartment (4, 71) of the vessel (3, 70) or from the compartment (4, 71) to the floating or shore storage facility (77) via an insulating pipe (73, 79, 76, 81).

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