Ships used to transport or use cold fluids

Abstract

The present invention relates to a ship (3) for transporting cold fluids, the ship (3, 70) comprising: a load-bearing structure comprising a hull extending in the longitudinal direction and at least one transverse cofferdam (9) subdividing the hull into a plurality of parts, one transverse cofferdam (9) or each transverse cofferdam (9) comprising 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 insulated tank (4) arranged in a portion of the hull adjacent to the transverse cofferdam (9); and gas management equipment for managing the gas environment in the interior space of the transverse cofferdam (9).

Description

Technical Field

[0001] The present invention relates to the field of ships for transporting cold fluids. In particular, the present invention relates to the field of ships comprising sealed and insulated tanks for transporting liquefied gases, in particular LNG, and to liquefied gas-powered ships, for example ships powered by LNG. Background Art

[0002] Liquefied natural gas is stored in a gas-liquid two-phase equilibrium state at low temperatures in sealed and insulated tanks. In particular, liquefied natural gas (LNG) is stored at approximately -162°C under atmospheric pressure.

[0003] Tanks can be produced using various technologies, particularly in the form of integrated membrane cargo tanks or self-supporting tanks. The thermal insulation and adjacent compartments of LNG storage tanks are sources of heat flow that tend to heat the tank contents, causing evaporation of the LNG. The gas produced by natural evaporation is typically used to supply gas-consuming components to fully utilize the gas. Therefore, on LNG tankers, the evaporated gas is used to drive the propulsion units to propel the ship. However, while this approach allows for the optimization of the gas produced by natural evaporation in liquefied gas transport tanks, it does not allow for the reduction of the amount of gas produced by natural evaporation.

[0004] Furthermore, LNG contained in tanks is generally intended to be transported by ships rather than consumed by them. Therefore, the evaporation rate of the liquid contained in the tanks, often referred to as the "boil-off rate" (BOR), is a major issue, particularly leading to the loss of some of the cargo.

[0005] Several solutions are known for reducing the BOR or for recovering the vaporized gas in the tanks containing LNG, in particular:

[0006] a reliquefaction plant via a heat exchanger for condensing the gases produced by natural evaporation;

[0007] Increase the thickness of the insulation in the tank; or

[0008] Use more thermally efficient materials.

[0009] However, these solutions are reaching a saturation point and no longer allow a favourable performance-cost ratio to be obtained. Furthermore, the modification of tanks intended to receive LNG is complex and expensive.

[0010] Liquefied natural gas (LNG) is also often placed on ships to form a fuel, or at least one of a combination of fuels, for propulsion of all types of ships, such as LNG carriers or LNG tankers, oil tankers, and even container ships. This is known as an "LNG-fueled ship," or LFS. In such ships, at least one LNG tanker is typically located near a heat source, such as the engine room. Summary of the Invention

[0011] One idea behind the invention is to provide a vessel in which the temperature in the interior of the transverse cofferdam can be reduced so that the heat flow between the interior and the adjacent tanks is reduced and thus the evaporation rate in the tanks containing the cold liquid is reduced. A target is to reduce the BOR by 5% or 6%.

[0012] One idea behind the invention is to reduce heat flow between any hollow space of the ship adjacent to the LNG storage tanks and the external environment, in particular between the ballast water and the atmospheric air, thereby for example reducing heat flow through the periphery of the cofferdam.

[0013] Another idea behind the present invention is to reduce the heat flow in the cofferdam located between the heat source and the LNG tank to protect the heat source and the LNG tank from temperature variations.

[0014] Another idea behind the present invention is to manage the gas environment in the cofferdam of a ship.

[0015] Another idea behind the present invention is to reduce the temperature in the cofferdam to reduce the BOR in the LNG storage tank.

[0016] Another idea behind the present invention is to obtain an equilibrium temperature, for example -15 degrees Celsius (° C.) or -25° C., in the cofferdam while maintaining its integrity.

[0017] The temperature drop in the hollow space of a ship, and in particular in the cofferdam, leads to the risk of frost forming in the cofferdam's interior, particularly on the walls or insulation. This risk is particularly due to the humidity present in the ambient air. The formation of such frost carries the risk of reducing the thermal performance of the insulation and corroding the cofferdam walls.

[0018] Therefore, the present invention proposes to integrate a gas management device to manage the gas environment in the hollow space of the ship, such as in the cofferdam, thereby solving the technical problems already described.

[0019] limited:

[0020] The term "fluid" includes liquids and gases.

[0021] The terms "cold" or "cryogenic" are defined as low temperatures, such as negative temperatures (°C), such as -50°C or -162°C.

[0022] The term "cofferdam" is defined as a hollow, divided space in a vessel adjacent to at least one tank. A cofferdam may also be referred to as a "caisson" or "dry net."

[0023] The term "valve" means a valve or a valve.

[0024] According to one embodiment, the present invention provides a vessel for transporting cold fluids, the vessel comprising:

[0025] a load-bearing structure comprising a hull extending in a longitudinal direction and at least one transverse cofferdam dividing the hull into a plurality of sections, the or each transverse cofferdam comprising a pair of transverse bulkheads defining an interior space of the transverse cofferdam and an upper wall enclosing said interior space;

[0026] at least one sealed and insulated tank disposed in a portion of the hull adjacent to the transverse cofferdam;

[0027] Gas management equipment, which is used to manage the gas environment in the internal space of the transverse cofferdam, wherein the gas management equipment includes:

[0028] a dry air supply line including a first end portion located outside the transverse cofferdam and connected to a dry air generator for supplying dry air, and a second end portion exposed to an interior space of the transverse cofferdam;

[0029] an inlet valve installed on the dry air supply line;

[0030] a gas discharge line including a first end portion exposed in an inner space of the transverse cofferdam and a second end portion exposed to the outside of the vessel;

[0031] a discharge valve mounted on the gas discharge line, the discharge valve being configured to open when a relative pressure in the interior space rises above a first threshold;

[0032] a pressure sensor configured to detect a relative pressure in an interior space of the transverse cofferdam;

[0033] a pressure regulator connected to the pressure sensor and the inlet valve, the pressure regulator being configured to:

[0034] The inlet valve is opened when the relative pressure in the interior space drops below a second threshold value, which is a positive value lower than the first threshold value.

[0035] By means of these features, the pressure of the gaseous environment in the interior space of the transverse cofferdam is regulated to remain above ambient pressure, thereby preventing the spontaneous ingress of ambient air and moisture. These features particularly prevent corrosive damage to various components located within the interior space of the transverse cofferdam. Furthermore, despite temperature variations in the interior space and changes in ambient pressure, the gas management device allows the relative pressure to be maintained within a positive range between a second threshold and a first threshold. The first threshold limits the pressure exerted on the paired transverse bulkheads and upper wall of the transverse cofferdam.

[0036] Depending on the embodiment, such a vessel may include one or more of the following features.

[0037] According to one embodiment, the pressure regulator may also be configured to:

[0038] When the pressure in the internal space rises above a third threshold value within the range between the second threshold value and the first threshold value, the inlet valve is closed.

[0039] By means of these hysteresis features, the operation of the inlet valve is optimized and also avoids excessive opening or closing times of the inlet valve which could lead to premature wear of the equipment.

[0040] According to one embodiment, the difference between the third threshold value and the second threshold value is less than 2 kPa (kilopascals) (20 mbarg).

[0041] According to one embodiment, the difference between the third threshold value and the second threshold value is in the range between 0.5 kPa and 1.5 kPa, for example the difference is 1 kPa.

[0042] According to one embodiment, a pressure regulator is further connected to the discharge valve, the pressure regulator being further configured to:

[0043] When the pressure in the interior space rises above a first threshold value, the discharge valve is opened.

[0044] With the aid of these features, it is facilitated to program and manage the opening and closing parameters of the inlet valve and the discharge valve of the gas management device and can be managed centrally.

[0045] According to one embodiment, the pressure regulator is further configured to:

[0046] The discharge valve is closed when the pressure in the internal space drops below a fourth threshold value, which is within a range between the first threshold value and the second threshold value.

[0047] By means of these hysteresis features, the operation of the discharge valve is optimized and also avoids excessive opening or closing times of the discharge valve, which could lead to premature wear of the equipment.

[0048] According to one embodiment, the difference between the fourth threshold value and the first threshold value is less than 2 kPa (20 mbarg).

[0049] According to one embodiment, the difference between the fourth threshold value and the first threshold value is in the range between 0.5 kPa and 1.5 kPa, for example the difference is 1 kPa.

[0050] According to another embodiment, the discharge valve is a mechanically opened and closed discharge valve configured to:

[0051] The discharge valve opens when the relative pressure in the interior space rises above a first threshold value.

[0052] According to one embodiment, the discharge valve is configured as follows:

[0053] The lateral weir is closed when the pressure in the inner space thereof drops below a fourth threshold value, the fourth threshold value being within a range between the first threshold value and the second threshold value.

[0054] 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, a spring or flap safety valve.

[0055] According to one embodiment, the second threshold value is in the range between 1 kPa (10 mbarg) and 10 kPa (100 mbarg), preferably, the second threshold value is in the range between 2 kPa (20 mbarg) and 5 kPa (50 mbarg).

[0056] According to one embodiment, the second threshold value is 2 kPa or 5 kPa.

[0057] According to one embodiment, the first threshold value is within the range between 12 kPa (120 mbarg) and 18 kPa (180 mbarg), preferably, the first threshold value is within the range between 13 kPa (130 mbarg) and 15 kPa (150 mbarg).

[0058] According to one embodiment, the first threshold value is 14 kPa (140 mbarg).

[0059] According to one embodiment, the gas management device further comprises a gas relief valve installed on the gas discharge line upstream of the discharge valve to allow extraction of a volume of gas from the inner space of the transverse cofferdam.

[0060] Thanks to these features, a volume of gas can be easily extracted from the interior of the transverse weir, i.e., without having to enter the interior of the transverse weir or having to extract a gas sample from the second end of the discharge line, which is not always easily accessible. Furthermore, this allows the gas to be extracted without operating the discharge valve and therefore without interrupting its operation.

[0061] According to one embodiment, the paired transverse bulkheads are made of a steel grade selected from the group consisting of D-grade, E-grade, DH-grade and EH-grade steel grades.

[0062] According to one embodiment, the thickness of the pair of transverse bulkheads is greater than or equal to 10 mm, for example, the thickness is in the range between 10 mm and 50 mm, preferably, the thickness is in the range between 15 mm and 20 mm.

[0063] According to one embodiment, the longitudinal walls of the cofferdam are made of a steel grade selected from the group consisting of D-grade, E-grade, DH-grade and / or EH-grade. Steel grades D and / or E are preferred.

[0064] According to one embodiment, the thickness of the longitudinal wall of the cofferdam is greater than or equal to 10 mm, for example, the thickness is in the range between 10 mm and 50 mm, preferably, the thickness is in the range between 15 mm and 20 mm.

[0065] The specific characteristics of the indicated steel grades are described in the International Gas Code.

[0066] By means of these features, temperatures below -15°C and / or -25°C can be achieved in the inner space of the transverse cofferdam without damaging the paired transverse bulkheads.

[0067] According to one embodiment, the transverse weir comprises thermal insulation.

[0068] By virtue of these features, heat flow between the sealed and insulated tank and one or more heat sources located in the vicinity of the vessel is reduced.

[0069] According to one embodiment, the thermal insulation is located on the outer surface of the cofferdam. According to one embodiment, the thermal insulation is located on the outer surface of the pair of transverse bulkheads.

[0070] According to one embodiment, the thermal insulation is located in the inner space of the transverse cofferdam, the thermal insulation preferably being attached to the longitudinal walls of the transverse cofferdam, said longitudinal walls comprising a portion of the inner hull and the upper wall.

[0071] Thanks to these features, the gas management device allows the insulation to be kept dry. Therefore, the insulation is not damaged or flooded by moisture. As a result, the thermal performance of the insulation is optimally maintained.

[0072] According to one embodiment, when the transverse weir is adjacent to a single tank, the insulation also covers the bulkhead of the pair of bulkheads that is furthest from said tank.

[0073] According to one embodiment, the heat insulating portion is insulating glass wool, which is covered with an insulating metal foil or foam on its outer surface. Preferably, the heat insulating portion is insulating glass wool covered with an insulating metal foil, such as an aluminum layer on its outer surface. According to one embodiment, the insulating foam is polyurethane foam (PUF).

[0074] According to one embodiment, the density of the insulating glass wool is between 20 kg / m 3 and 60kg / m 3 In the range between, preferably, the density is 22kg / m 3 .

[0075] According to one embodiment, the density of the thermal insulation foam is between 20 kg / m 3 and 80kg / m 3 In the range between , preferably, the density is 50kg / m 3 .

[0076] By means of these features, heat losses are reduced and thus the management of the gas environment in the inner space of the transverse cofferdam is facilitated.

[0077] According to one embodiment, the thickness of the insulating glass wool is in the range between 100 mm and 400 mm. The thickness of the insulating glass wool is preferably in the range between 200 mm and 350 mm, for example 200 mm.

[0078] According to one embodiment, the thickness of the thermal insulation foam is in the range between 100 mm and 400 mm, preferably the thickness of the thermal insulation foam is in the range between 200 mm and 350 mm, for example 200 mm.

[0079] By means of these features, temperatures below -15°C and / or -25°C can be achieved in the inner space of the transverse cofferdam.

[0080] According to one embodiment, the drying air supply line passes through the upper wall.

[0081] According to one embodiment, the second end of the drying air supply line is exposed near the bottom wall of the transverse weir.

[0082] According to one embodiment, the gas discharge line passes through the upper wall.

[0083] According to one embodiment, the first end of the gas discharge line is located near the upper wall.

[0084] By means of these features, the supply of dry air to the inner space of the transverse cofferdam allows the gas located in the inner space of the transverse cofferdam to be discharged more efficiently via the discharge line.

[0085] According to one embodiment, the drying air supply line and the gas exhaust line are manufactured from steel or another material selected from stainless steel, D-grade steel, E-grade steel, DH-grade steel and / or EH-grade steel.

[0086] According to one embodiment, the moisture content in the inner space of the transverse cofferdam is kept below 25%, such as below 15% and preferably below 5%.According to one embodiment, the moisture content in the inner space of the transverse cofferdam is close to 0%.

[0087] By means of these features, the formation of frost on the insulation or on the cofferdam walls is limited. Thus, the risk of reducing the thermal performance capabilities of the insulation or the risk of corroding the cofferdam walls is greatly reduced.

[0088] According to one embodiment, the drying air has a dew point temperature of less than -15°C, preferably less than -20°C, such as a temperature less than or equal to -45°C or such as a temperature between -20°C and -40°C or between -25°C and -30°C.

[0089] According to one embodiment, the pressure sensor is a piezoresistive pressure sensor that measures gauge pressure (GP). According to one embodiment, the sensor is made of corrosion-resistant steel that can withstand negative temperatures, for example, the sensor is made of SUS316L steel. According to one embodiment, the pressure sensor includes a diaphragm.

[0090] According to one embodiment, the pressure regulator is electronic.

[0091] According to one embodiment, the inlet valve and / or the discharge valve are solenoid valves.

[0092] According to one embodiment, a plurality of inlet valves are installed in series on the drying air supply line or are branched on the drying air supply line. These inlet valves may be different.

[0093] According to one embodiment, a plurality of discharge valves are installed in series on the gas discharge line or branched on the gas discharge line. These discharge valves may be different.

[0094] By means of these features, the ship's gas management device is better adapted to the ship in which it is integrated. Furthermore, these features allow the safety and ease of monitoring and maintenance of the ship's gas management device to be enhanced.

[0095] According to one embodiment, the dry air generator is a device for drying atmospheric air by heating it.

[0096] According to one embodiment, the dry air generator is a device that provides dry air having a dew point temperature below -40°C, preferably a dew point temperature of -45°C.

[0097] According to one embodiment, the dry air generator is operated at a temperature between 10,000 m 3 / h and 20,000m 3 / h, for example, 15,000m 3 The dry air is supplied into the inner space of the transverse cofferdam at a flow rate of 100 psi / h to fill the transverse cofferdam with the dry air.

[0098] According to one embodiment, the dry air generator is operated at a temperature between 50 m 3 / h and 500m 3 Dry air is supplied into the interior space of the transverse cofferdam at a flow rate within a range of 100 Å / h to manage the gas environment in the interior space of the transverse cofferdam.

[0099] According to one embodiment, the dry air generator used is a dry air generator already installed on board. This reduces costs by eliminating the need to provide a dry air generator to the gas management equipment for managing the gas environment in the interior space of the transverse cofferdam.

[0100] According to another embodiment, a gas management device for managing the gas environment in the interior space of a transverse cofferdam comprises:

[0101] a dry air supply line, the dry air supply line including a first end portion and a second end portion, the first end portion being located outside the transverse cofferdam and connected to a first dry air generator for supplying dry air, the second end portion being exposed to an inner space of the transverse cofferdam, wherein a first inlet valve is installed on the dry air supply line,

[0102] The dry air generator is configured to generate air at a rate greater than 10,000 m 3 / h, for example, between 10,000m 3 / h and 20,000m 3 The dry air is delivered to the inner space of the cofferdam at a flow rate of between / h;

[0103] A second dry air generator is connected to a dry air supply line branched from the first dry air generator, wherein a second inlet valve is installed between the second dry air generator and the dry air supply line, the second dry air generator being configured to supply air at a rate of less than 10,000 m 3 / h, for example, between 50m 3 / h and 500m 3The dry air is delivered to the inner space of the cofferdam at a flow rate of between / h.

[0104] Advantageously, the first dry air generator, the dry air supply line and the first inlet valve are components that are typically present in an LNG tanker ship.This embodiment is particularly advantageous because it limits additional components to be installed on board the ship.

[0105] According to one embodiment, the dry air generator is connected to the pressure regulator, and the pressure regulator is further configured to:

[0106] When the relative pressure in the interior space drops below a second threshold value, or in other words, when the inlet valve opens, discharge of dry air from the dry air generator into the supply line is enabled.

[0107] According to one embodiment, the present invention also provides a transmission system for cold liquid products, which includes: the above-mentioned ship; an insulating pipeline arranged to connect a tank installed in the hull of the ship to a floating or onshore storage device; and a pump for feeding the cold liquid product flow from the floating or onshore storage device to the tank of the ship through the insulating pipeline, or for feeding the cold liquid product flow from the tank of the ship to the floating or onshore storage device through the insulating pipeline.

[0108] According to one embodiment, the present invention also provides a method for loading or unloading such a vessel, wherein the cold liquid product is transferred from a floating or onshore storage facility to a tank of the vessel via an insulated pipeline, or the cold liquid product is transferred from a tank of the vessel to a floating or onshore facility via an insulated pipeline.

[0109] By means of these features, the BOR can be reduced by 2% to 6%, preferably 5% to 6%.

[0110] Some aspects of the invention are based on the idea of ​​drying the interior of the transverse cofferdams in order to allow the temperature in the interior of the transverse cofferdams to be lowered without damaging the vessel.

[0111] Such gas management equipment of the ship can be integrated via piping and valves already present in the ship, for example already present in an LNG tanker ship.In addition, additional management valves or safety valves can be integrated into the ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] The present invention will be better understood and further objects, details, features and advantages of the present invention will become more apparent throughout the following description of several specific embodiments thereof, which are provided by way of non-limiting examples only, with reference to the accompanying drawings.

[0113] [ Figure 1 ] Figure 1is a graph showing the temperature variation over time in the cofferdam of a typical LNG tanker during operation. Figure 1 It does not form part of the present invention but is useful for understanding.

[0114] [ Figure 2 ] Figure 2 is a cross-sectional view along a longitudinal axis of a liquefied natural gas carrier according to one embodiment.

[0115] [ Figure 3 ] Figure 3 According to one embodiment, it can be used in Figure 2 A perspective cutaway view of the transverse cofferdam amidships.

[0116] [ Figure 4 ] Figure 4 According to one embodiment, it can be used in Figure 2 Cross-sectional view of a transverse cofferdam in a ship, the transverse cofferdam including a thermal insulation portion.

[0117] [ Figure 5 ] Figure 5 FIG. 1 is a diagram showing a device according to an embodiment of the present invention. Figure 2 Schematic diagram of a transverse cofferdam in a ship with a gas management device for managing the gas environment in the internal space of the transverse cofferdam.

[0118] [ Figure 6 ] Figure 6 FIG. 1 is a diagram showing a device according to another embodiment of the present invention. Figure 2 Schematic diagram of a transverse cofferdam in a ship with a gas management device for managing the gas environment in the internal space of the transverse cofferdam.

[0119] [ Figure 7 ] Figure 7 is a schematic cross-sectional representation of an LNG tanker ship including tanks and a pier for loading / unloading the tanks according to one embodiment.

[0120] [ Figure 8 ] Figure 8 A schematic cross-sectional view in the transverse direction of a petroleum tanker is shown.

[0121] [ Figure 9 ] Figure 9 is a cross-sectional view of the stern of a ship including a sealed and insulated tank for storing liquefied fuel gas, the tank being located behind the bridge in the longitudinal direction of the ship. DETAILED DESCRIPTION

[0122] Figure 1A diagram showing the temperature T (°C) of the cofferdam as a function of time (t) is shown. Noticeable temperature variations are common when the ship is sailing. In fact, when the ship comprises tanks filled with LNG, step 1 involves emptying 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 drops significantly. According to step 2, when the ship unloads LNG or uses LNG, part of the tanks is therefore emptied and the ballast tanks are filled with seawater to optimize navigation. Therefore, the temperature of the cofferdam varies via the heat transfer from the seawater in the ballast tanks to the cofferdam. Typically, during step 2, the temperature in the cofferdam increases. The ship thus completes the cycle, repeating steps 1 and 2. Therefore, it is difficult to regulate the temperature in the cofferdam.

[0123] Figure 2 A ship 3 is shown which is equipped with storage and transportation equipment for liquefied natural gas, comprising four sealed and insulated tanks 4. Each tank 4 is associated with an exhaust mast 5 which is arranged on the deck 12 of the ship 3 and which allows the gas in the gaseous phase to escape when there is an overpressure in the associated tank 4. An engine compartment 6 is arranged at the stern of the ship 3, which compartment generally comprises a hybrid-powered steam turbine which operates by burning diesel fuel or by burning boil-off gases originating from the tanks 4. The tanks 4 have a longitudinal dimension which extends in the longitudinal direction of the ship 3. Each tank 4 is delimited at each of its longitudinal ends by a pair of transverse bulkheads 7, 8 which define a sealed interstitial space known as a "cofferdam" 9. The tanks 4 are thus separated from each other by the transverse cofferdams 9. It can thus be observed that the tanks 4 are each arranged inside a load-bearing structure formed on the one hand by the double hull of the vessel 3 and on the other hand by one of the transverse bulkheads 7 , 8 of each of the cofferdams 9 delimiting the tanks 4 .

[0124] Ships according to embodiments of the present invention can include various types of tanks, such as membrane tanks for storing liquefied gas, and are not limited to a specific tank. Ship 4 has a multi-layer structure (not shown) that includes, from the outside to the inside: a secondary thermal insulation barrier comprising insulating elements abutting against a load-bearing structure; a secondary sealing membrane abutting against the secondary thermal insulation barrier; a primary thermal insulation barrier comprising insulating elements abutting against the secondary sealing membrane; and a primary sealing membrane intended to come into contact with the liquefied gas contained in the tank. The primary sealing membrane defines the interior space of tank 4 for receiving the liquefied gas.

[0125] The liquefied gas intended to be stored in the tank may in particular be liquefied natural gas (LNG), i.e. a gaseous mixture comprising mainly methane and one or more other hydrocarbons. The liquefied gas may also be ethane or liquefied petroleum gas (LPG), i.e. a mixture of hydrocarbons produced from oil refining comprising essentially propane and butane.

[0126] Figure 3 A perspective cross-sectional view of a transverse cofferdam 19 according to one embodiment is shown in a catamaran vessel comprising an outer hull 10 and an inner hull 15. The transverse cofferdam 19 comprises a pair of transverse bulkheads defining an inner space 13 of the transverse cofferdam 19. Figure 3 Only one of the two transverse bulkheads 17 is shown in order to illustrate the interior space 13 of the transverse cofferdam 19. The transverse cofferdam 19 also includes an upper wall 37 that encloses the interior space 13. For example, the upper wall 37 can be a wall parallel to the upper deck 12 of the ship. The portion of the inner hull 15 located opposite the upper wall 37 defines the bottom of the interior space of the transverse cofferdam 19. The ship also includes a ballast tank 41 located outside the transverse cofferdam 19. The ballast tank 41 is formed by the bottom portion of the space between the inner hull 15 and the outer hull 10 of the ship.

[0127] The transverse weir 19 also includes a reinforcement structure 14 that crisscrosses the interior space 13 in a non-sealed manner. The interior space 13 of the transverse weir 19 can accommodate a heating system 16 for controlling the temperature of the transverse weir 19. The heating device is formed by a twisted pipe through which ethylene glycol or another heated antifreeze solution circulates.

[0128] Figure 4 An embodiment of a transverse weir 19 is shown, which also includes insulation 40, which is located in the interior space 23 of the transverse weir. The insulation 40 is attached to the longitudinal walls of the transverse weir 29, which comprise a portion of the inner hull 15 and the upper wall 37. If the transverse weir 19 is located between two tanks 4, only two transverse bulkheads 17 are not covered with insulation 40.

[0129] Figure 5 FIG2 shows a gas management device of a ship according to an embodiment, which is used to manage the gas environment in the inner space 23 of the transverse cofferdam 29 of the ship. The transverse cofferdam 29 includes a pair of transverse bulkheads 107, 109 defining the inner space 23 of the transverse cofferdam and an upper wall 37 that closes the inner space. Figure 4Likewise, the transverse cofferdam 29 comprises an insulation 40 in the inner space 23 of the transverse cofferdam, wherein the insulation is attached to the longitudinal walls of the transverse cofferdam 29 , said longitudinal walls comprising a portion of the inner hull 15 and the upper wall 37 .

[0130] The ship's gas management equipment includes:

[0131] A dry air supply line 30 passes through the upper wall 37 of the transverse cofferdam 29 and includes a first end portion, the first end portion being located outside the transverse cofferdam 29 and connected to the dry air generator 31, and a second end portion being exposed in the internal space 23 of the transverse cofferdam 29 near the bottom of the cofferdam, i.e., near a portion of the inner hull 15 located opposite the upper wall 37.

[0132] The ship's gas management equipment also includes:

[0133] an inlet valve 32 mounted on the dry air supply line 30 and located outside the transverse cofferdam 29;

[0134] a gas discharge line 33 passing through the upper wall 37 and comprising a first end exposed in the internal space 23 of the transverse cofferdam 29 and a second end exposed to the outside of the ship;

[0135] a discharge valve 34 located outside the transverse cofferdam 29 and installed on a gas discharge line 33;

[0136] a pressure sensor 35 configured to detect the relative pressure in the interior space 23 of the transverse cofferdam 29;

[0137] A pressure regulator 36 is located outside the transverse weir 29 and is connected to the pressure sensor 35 , the inlet valve 32 and the discharge valve 34 .

[0138] In this case, the pressure regulator 36 is configured to:

[0139] The inlet valve 32 is opened when the relative pressure in the inner space 23 drops below a second threshold value, which is a positive value, for example, about 5 kPa;

[0140] The discharge valve 34 is opened when the relative pressure in the interior space 23 rises above a first threshold value, for example, about 15 kPa, which is higher than a second threshold value. In addition, the pressure regulator 36 can be configured to perform one or more of the following actions:

[0141] When the relative pressure in the internal space 23 rises above a first threshold, or when the relative pressure in the internal space 23 rises to a third threshold within a range between the second threshold and the first threshold in the case of hysteresis, the inlet valve 32 is closed;

[0142] When the relative pressure of the interior space 23 drops below the second threshold, or when the relative pressure of the interior space 23 drops to a fourth threshold within the range between the first and second thresholds with hysteresis, the discharge valve 34 is closed.

[0143] Such gas management equipment may be integrated, for example to regulate the gas environment of weirs 9 and 19 as shown above.

[0144] Figure 6 FIG2 shows a gas management device according to another embodiment, which is used to manage the gas environment in the inner space 23 of the transverse cofferdam 29. The pressure regulator 136 is still connected to the pressure sensor 35 and the inlet valve 32. Figure 5 The difference is that the discharge valve 134 is a mechanically opened and closed discharge valve 134, which is not connected to the pressure regulator 136 and which opens and closes automatically depending on the pressure prevailing in the interior space 23. The mechanically opened and closed discharge valve 134 is designed to open when the relative pressure in the interior space 23 rises above a first threshold value and to close when the relative pressure in the interior space 23 falls below the first threshold value, optionally with a hysteresis. To this end, the mechanically opened and closed discharge valve 134 comprises, for example, a spring closing mechanism or a wing closing mechanism. This mechanically opened and closed discharge valve 134 performs a safety function because it specifically prevents damage that could be caused by an overpressure in the interior space 23 of the transverse cofferdam 29.

[0145] The gas management device also includes a gas relief valve 18. The gas relief valve 18 is installed on the gas discharge line 33 outside the transverse cofferdam 29 and upstream of the discharge valve 134 that is mechanically opened and closed. Therefore, a certain amount of gas can be extracted from the interior space 23 of the transverse cofferdam 29 to analyze the gas environment or temperature of the interior space 23 of the transverse cofferdam 29. Therefore, the gas environment in the interior space 23 of the transverse cofferdam 29 can be adjusted. The embodiments described with reference to the drawings are not limited to a specific type of transverse cofferdam, for example, Figure 6 The embodiment described in can be applied to the cofferdam described in one of the preceding figures.

[0146] The transverse weir 29 comprises an insulation 40 covering the inner surface of the longitudinal walls of the transverse weir 29, including the upper wall 37 and the inner hull 15, over the entire periphery of the inner space 23. Figure 5 In the same. Figure 6 In the embodiment shown in , the transverse cofferdam 29 further comprises 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 limits the heat flow with the ballast water and the ambient air, and the thermal insulation 140 also limits the heat flow with the compartments adjacent to the transverse bulkhead 107, and thus for example with the engine compartment 6 or any other heat source having a temperature higher than that of the vessel 4.

[0147] Insulation 40 or 140 may be glass wool covered on the outside with a vapor barrier, such as an aluminum layer. The glass wool may be attached by protruding spikes (not shown) having a first end welded to the wall of transverse cofferdam 29 and passing through the glass wool. To hold the glass wool in place, a locking device, such as a clamping fastener, is added above the glass wool and on the second end of the spike.

[0148] about Figure 8 and Figure 9 , embodiments are described above in which the above-described gas management equipment is installed in other types of ships.

[0149] For example, in a petroleum tanker 80, as Figure 8 As shown in the cross-sectional view in , the vessel 80 comprises a sealed and insulated tank 4 positioned between two cargo tanks 42 filled with cargo, for example with oil.

[0150] The oil has a higher temperature than the LNG in the tank 4. The oil can also be heated by a heating device to increase the viscosity of the oil, thereby facilitating loading or unloading of the oil. For example, the oil can have a temperature of 60°C.

[0151] Each cargo tank 42 is separated from the sealed and insulated tank 4 by a transverse weir 39. Transverse weirs 39 are similar to transverse weirs 29 described above and include insulation on at least the interior surface of the transverse bulkheads, thereby limiting heat flow 43 to adjacent compartments, specifically, limiting heat flow between tanks 4 and 42 by limiting heat transfer from cargo tank 42 to tank 4. In other words, tank 4 is thermally insulated from the petroleum stored in cargo tank 42 at a higher temperature than the liquefied natural gas stored in tank 4. Similarly, cargo tank 42 is thermally insulated from the LNG in tank 4.

[0152] Similarly, Figure 9The ship 90 shown in FIG is an LNG powered ship. The ship 90 may be a container ship or a bulk carrier. A bulk carrier is a ship designed for transporting solid bulk products. Therefore, in a manner known per se, in front of the bridge 44 of the ship 90 in the longitudinal direction X'-X of the ship 90, the ship 90 comprises one or more cargo holds 45 for transporting solid bulk products. The cargo holds 45 are spaced apart in a manner known per se in the longitudinal direction X'-X of the ship 90. It should be noted that in FIG Figure 9 Only one of these holds 45 is schematically shown, namely the cargo hold 45 closest to the bridge 44. The ship 90 also includes a sealed and insulated tank 4 containing LNG, which is intended to supply the propulsion system 46. The tank 4 is located behind the bridge 6 in the longitudinal direction X'-X. The tank 4 is separated from the heat sources—that is, the bridge, the propulsion system 46, and the cargo hold 45—by a transverse weir 49. The transverse weir 49 notably includes the insulation and gas management equipment described above. Thus, as in the ship described above, the heat flow between the heat source and the tank 4 is significantly limited.

[0153] The gas management device described above enables a method to be performed comprising the following steps:

[0154] - when the relative pressure in the interior of the cofferdam drops below 5 kPa, dry air is fed into the interior of the transverse cofferdam via a dry air generator supplied with a dry air supply line, so that the cofferdam only admits dry air and not humid ambient air,

[0155] - When the relative pressure rises above 14 kPa, the gas is discharged from the internal space of the transverse cofferdam to the space outside the transverse cofferdam through the discharge pipeline.

[0156] Therefore, the temperature of the inner space of the cofferdam can be lowered to -15 degrees Celsius (° C.) or -25° C. without damaging the ship.

[0157] The values ​​shown can be adjusted depending on the desired gas management.

[0158] Reference Figure 7 , a cross-sectional view of an LNG tanker ship 70 shows a sealed and insulated tank 71 of generally prismatic shape installed in the ship's double hull 72. The wall of the tank 71 includes: a primary sealing barrier intended to be in contact with the LNG contained in the tank; a secondary sealing barrier arranged between the primary sealing barrier and the ship's double hull 72; and two thermal insulation barriers arranged between the primary sealing barrier and the secondary sealing barrier and between the secondary sealing barrier and the double hull 72, respectively.

[0159] In a manner known per se, the loading / unloading piping 73 arranged on the upper deck of the vessel can be connected by means of appropriate connections to a marine or port terminal for transferring LNG cargo from or to the tanks 71 .

[0160] Figure 7 An example of a marine terminal is shown, including a loading and unloading station 75, a submarine pipeline 76, and an onshore facility 77. The loading and unloading station 75 is a fixed offshore facility that includes a movable arm 74 and a tower 78 that supports the movable arm 74. The movable arm 74 supports a bundle of insulated flexible pipes 79 that can be connected to a loading / unloading pipeline 73. The movable arm 74 is orientable to accommodate all types of LNG tanker ship gauges. Connecting pipelines (not shown) extend within the interior of the tower 78. The loading and unloading station 75 allows LNG tanker ships 70 to be loaded from or unloaded to the onshore facility 77. The facility includes a liquefied gas storage tank 80 and a connecting pipeline 81 that is connected to the loading and unloading station 75 via a submarine pipeline 76. The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore facility 77 over a longer distance, for example 5 km, which allows the LNG tanker ship 70 to be kept at a greater distance from the coast during loading and unloading operations.

[0161] In order to generate the pressure required for the transfer of the liquefied gas, a pump on board the ship 70 and / or a pump provided on the land facility 77 and / or a pump provided on the loading and unloading station 75 may be used.

[0162] Although the present invention has been described with reference to a number of specific embodiments, it is clear that the present invention is by no means limited thereto, and if technical equivalents of the described devices and combinations thereof fall within the scope of the present invention, the present invention includes all technical equivalents and combinations of these technical equivalents.

[0163] The gas management equipment for managing the gas environment in the internal space of the transverse cofferdam may also, for example, include a branch line comprising a manual valve across, for example, an inlet valve or a discharge valve, or even an alarm system (PAL, PAH, PALL, PAHH) linked to a pressure sensor, but this does not depart from the scope of the present invention.

[0164] Some of the components, in particular the components of the pressure regulator, can be manufactured in various forms, either monolithic or distributed, using hardware and / or software components. Hardware components that can be used include specialized 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.

[0165] Use of the verb "comprise" or "include" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim.

[0166] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

1. A vessel (3, 70) for transporting cold fluids, 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) dividing the hull into a plurality of parts, at least one transverse cofferdam (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) closing the interior space (13, 23); at least one sealed and insulated tank (4, 71), said tank (4, 71) being arranged in a portion of said hull (110) adjacent to said transverse cofferdams (9, 19, 29); A gas management device for managing the gas environment in the internal space (13, 23) of the transverse cofferdam (9, 19, 29), wherein the gas management device comprises: a dry air supply line (30), the dry air supply line (30) comprising a first end and a second end, the first end of the dry air supply line (30) being located outside the transverse cofferdam (9, 19, 29) and connected to a dry air generator (31) for supplying dry air, and the second end of the dry air supply line (30) being exposed to the inner space (13, 23) of the transverse cofferdam (9, 19, 29); an inlet valve (32), the inlet valve (32) being installed on the dry air supply line (30); a gas discharge line (33), the gas discharge line (33) comprising a first end and a second end, the first end of the gas discharge line (33) being exposed in the inner space (13, 23) of the transverse cofferdam (9, 19, 29), and the second end of the gas discharge line (33) being exposed to the outside of the ship (3, 70); a discharge valve (34, 134) mounted on the gas discharge line (33), the discharge valve (34, 134) being configured to open when the relative pressure in the interior space (13, 23) rises above a first threshold; a pressure sensor (35) configured to detect relative pressure in the interior space (13, 23) of the transverse cofferdam; a pressure regulator (36, 136) connected to the pressure sensor (35) and the inlet valve (32), the pressure regulator (36, 136) being configured to: When the relative pressure of the internal space (13, 23) drops below a second threshold, the inlet valve (32) is opened, and the second threshold is a positive value lower than the first threshold.

2. The vessel according to claim 1, wherein: The pressure regulator (36, 136) is further configured to: The inlet valve (32) is closed when the pressure in the inner space (13, 23) rises above a third threshold value, the third threshold value being within a range between the second threshold value and the first threshold value.

3. The ship according to claim 2, wherein: The difference between the third threshold value and the second threshold value is less than 2 kPa.

4. A vessel according to any one of claims 1 to 3, wherein: The pressure regulator is also connected to the discharge valve (34, 134), and the pressure regulator is further configured to: When the pressure in the inner space (13, 23) rises above the first threshold value, the discharge valve (34, 134) opens.

5. The vessel according to claim 4, wherein: The pressure regulator is further configured to: The discharge valve is closed when the pressure in the inner space (13, 23) drops below a fourth threshold value, the fourth threshold value being within a range between the first threshold value and the second threshold value.

6. The vessel according to claim 5, wherein: The difference between the fourth threshold value and the first threshold value is less than 2 kPa.

7. A vessel according to any one of claims 1 to 3, wherein: The discharge valve (34, 134) is a discharge valve (34, 134) that is opened and closed mechanically, and the discharge valve (34, 134) is configured to: When the relative pressure in the inner space (13, 23) rises above the first threshold value, the discharge valve (34, 134) opens.

8. A vessel according to any one of claims 1 to 3, wherein: The second threshold is in the range between 1 kPa and 10 kPa.

9. A vessel according to any one of claims 1 to 3, wherein: The first threshold is in the range between 12 kPa and 18 kPa.

10. A vessel according to any one of claims 1 to 3, wherein: The gas management device also includes a gas relief valve (18) installed on the gas discharge line (33) upstream of the discharge valve (34, 134) to allow a volume of gas to be extracted from the internal space (13, 23) of the transverse cofferdam.

11. A vessel according to any one of claims 1 to 3, wherein: The pairs of transverse bulkheads (7, 8, 17, 107, 109) are made of steel grades selected from D grade, E grade, DH grade and EH grade.

12. A vessel according to any one of claims 1 to 3, wherein: The transverse cofferdam (9, 19, 29) comprises a heat insulating portion (40), and the heat insulating portion (40) is located in the inner space (13, 23) of the transverse cofferdam.

13. A vessel according to any one of claims 1 to 3, wherein: The transverse cofferdams (9, 19, 29) include thermal insulation on the outer surface of the transverse cofferdams.

14. The vessel of claim 12, wherein: The heat insulating portion (40) is heat insulating glass wool, and the outer surface of the heat insulating glass wool is covered with metal foil.

15. A delivery system for cold liquid products, wherein: The transmission system comprises: A vessel (3, 70) according to any one of claims 1 to 14; an isolation pipe (73, 79, 76, 81) arranged to connect the tank (4, 71) mounted in the hull (110) of the vessel to a floating or onshore storage facility (77); and A pump for supplying the cold liquid product stream from the floating or onshore storage facility through the insulated pipeline to the tank of the vessel, or for supplying the cold liquid product stream from the tank of the vessel through the insulated pipeline to the floating or onshore storage facility.

16. A method for loading or unloading a vessel (3, 70) according to any one of claims 1 to 14, wherein: Transferring the cold liquid product from a floating or onshore storage facility (77) to the tank (4, 71) of the ship (3, 70) through an insulated pipeline (73, 79, 76, 81), or transferring the cold liquid product from the tank (4, 71) of the ship (3, 70) to a floating or onshore storage facility (77) through an insulated pipeline (73, 79, 76, 81).

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