TW202300406A - Vessel for transporting or using a cold fluid - Google Patents

Abstract

The invention relates to a vessel (3) for transporting a cold fluid, the vessel (3, 70) comprising: a load-bearing structure comprising 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) comprising a pair of transverse bulkheads (7, 8) defining an internal space of the transverse cofferdam (9) and an upper wall closing said internal space; at least one sealed and thermally insulating tank (4) disposed in a segment of the hull adjacent to said transverse cofferdam (9); a gas management installation for managing a gaseous atmosphere in the internal space of the transverse cofferdam (9).

Description

Ships for transporting or using cold fluids

The invention relates to the field of ships for transporting a cold fluid. In particular, the invention relates to the field of ships comprising sealed and thermally insulated compartments for transporting a liquefied gas, in particular LNG, and ships powered by liquefied gas (for example, powered by LNG).

Liquefied natural gas is stored in a two-phase vapor-liquid equilibrium state at cryogenic temperatures in sealed and thermally insulated tanks, specifically, liquefied natural gas (LNG) is stored at about -162°C at atmospheric pressure.

Various techniques can be used to produce the tank, in particular in the form of an integrated membrane tank or a self-sustaining tank. The thermally insulating barriers of the LNG storage tanks and adjacent compartments are the source of heat flow that tends to heat the contents of the tanks causing the LNG to evaporate. Gas originating from natural evaporation is usually used to feed a gas consumer to make full use of the gas. Thus, on an LNG tanker, the boil-off gas is used to drive the propulsion units to propel the ship. However, although this practice allows optimization of the gas originating from the natural evaporation in the liquefied gas transport tank, it does not allow a reduction of its quantity.

Furthermore, LNG contained in tanks is usually intended to be transported and it is not consumed by the ship. Therefore, the evaporation rate of the liquid contained in the tank, commonly referred to as the "volatility rate" (BOR), is a major problem, leading in particular to the loss of some cargoes.

Several solutions are known for reducing the BOR or for recirculating evaporated gas in tanks containing LNG, in particular: A reliquefaction unit via a heat exchanger for condensing gases from natural evaporation; increase the thickness of insulation in tanks; or Use more thermally efficient materials. However, these solutions are reaching a saturation point and no longer allow to obtain a favorable performance-cost ratio. Furthermore, modifying a tank intended to receive LNG is complex and expensive.

Liquefied natural gas is also frequently placed on board ships for refueling or at least one of fueling to propel ships of all types, for example, LNG carriers or LNG tankers, tankers and container ships. This is known as an "LNG Fueled Ship" or LFS. In such ships, at least one LNG tank is usually located near a heat source, such as an engine room.

One idea behind the present invention is to provide a ship for which the temperature in the interior space of a transverse cofferdam can be reduced in order to reduce the heat flow between this interior space and an adjacent tank and thus reduce the temperature in the tank containing cold liquid. evaporation rate. One goal is to reduce, for example, the BOR by 5% or 6%.

One idea behind the present invention is to reduce heat flow between any hollow space of the ship adjacent to the LNG storage tanks and the external environment (specifically ballast water and atmosphere) to, for example, reduce the perimeter of the cofferdams heat flow.

Another idea behind the present invention is to reduce the heat flow in the cofferdams located between a heat source and an LNG tank to protect the heat source and the LNG tank from temperature changes.

Another idea behind the invention is to manage the gaseous atmosphere in the cofferdams of a ship.

Another idea behind the present invention is to reduce the temperature in the cofferdams to reduce the BOR in the LNG storage tanks.

Another idea behind the present invention is to achieve an equilibrium temperature (eg -15 degrees Celsius (°C) or -25°C) in the cofferdams while maintaining their integrity.

The temperature drop in the hollow spaces of the ship and in particular in the cofferdams leads to a risk of frost in the inner spaces of the cofferdams, in particular on the walls or in the insulation. This risk is especially due to the presence of humidity in the surrounding atmosphere. The occurrence of frost involves the risk of degrading the thermal performance capability of the insulation and of corroding the walls of the cofferdam.

Therefore, the present invention proposes to integrate a gas management device to manage a gas atmosphere in a hollow space of the ship, such as the cofferdams, to solve the technical problem described.

definition:

The term "fluid" includes liquids and gases.

The term "cold" or "low temperature" is defined as a low temperature, eg a negative temperature (in °C), such as -50°C or -162°C.

The term "cofferdam" is defined as a hollow separated space in a ship adjacent to at least one tank, which may also be called "caisson" or "dry grid".

The term "valve" refers to a valve or a valve gate.

According to one embodiment, the present invention provides a ship for transporting a cold fluid, the ship comprising: A load-bearing structure comprising a hull extending in a longitudinal direction and at least one transverse cofferdam subdividing the hull into a plurality of segments, the or each transverse cofferdam comprising an interior space delimiting the transverse cofferdam a pair of transverse bulkheads and one of the upper walls enclosing the internal space; at least one airtight and thermally insulated compartment housed in a section of the hull adjacent to the transverse cofferdam; A gas management device for managing a gas atmosphere in the interior space of the transverse cofferdam, wherein the gas management device comprises: a dry air supply line comprising a first end located outside the transverse cofferdam and connected to a dry air generator supplying dry air and a second end emerging in the inner space of the transverse cofferdam; an intake valve installed on the dry air supply line; a gas discharge line comprising a first end emerging in the interior space of the transverse cofferdam and a second end emerging outside the ship; 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 value; a pressure sensor configured to detect a relative pressure in the interior space of the transverse cofferdam; a pressure regulator connected to the pressure sensor and the intake valve, the pressure regulator configured to: The intake valve is opened when the relative pressure in the interior space drops below a second threshold, which is a positive value lower than the first threshold.

By virtue of these features, the pressure of the gaseous atmosphere in the inner space of the transverse cofferdam is regulated to remain higher than the ambient pressure, so that the spontaneous emergence of ambient air and moisture is prevented. These features allow in particular to prevent corrosion damage to the various elements located in the inner space of the transverse cofferdam. Furthermore, the gas management device allows maintaining the relative pressure in a positive range between the second threshold value and the first threshold value regardless of temperature variations in the interior space and variations in ambient pressure. By virtue of the first threshold value, the pressure exerted on the pair of transverse bulkheads and the upper wall of the transverse cofferdam can be limited.

Depending on the embodiment, such a boat may include one or more of the following features.

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

By virtue of these hysteresis characteristics, the operation of the intake valve is optimized and also the intake valve is avoided from opening or closing too many times, which can lead to premature wear of the device.

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

According to an embodiment, a 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 a difference of 1 kPa.

According to one embodiment, the pressure regulator is further connected to the discharge valve, the pressure regulator is further configured to: When the pressure in the inner space rises above the first threshold value, the discharge valve is opened.

By virtue of these features, the programming and management of the opening and closing parameters of the intake valve and the discharge valve of the gas management device is facilitated and can be centrally managed.

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 threshold value and the second threshold value, the discharge valve is closed.

By virtue of these hysteresis features, the operation of the discharge valve is optimized and also the discharge valve is avoided from being opened or closed too many times, which can lead to premature wear of the equipment.

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

According to an embodiment, a difference between the fourth threshold value and the first threshold value is in the range between 0.5 kPa and 1.5 kPa, eg a difference of 1 kPa.

According to another embodiment, the discharge valve is a mechanical opening and closing discharge valve configured to: opens when a relative pressure in the interior space rises above the first threshold.

According to one embodiment, the discharge valve is configured to: Closes when the pressure of the interior space of the transverse cofferdam drops below a fourth threshold between the first threshold and the second threshold.

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 tongue safety valve.

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

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

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

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

According to one embodiment, the gas management device further comprises a gas discharge valve mounted on the gas discharge line upstream of the discharge valve to allow extraction of a volume of gas from the interior space of the transverse cofferdam .

By virtue of these features, a certain amount of gas can be easily extracted from the inner space of the transverse cofferdam, i.e. without entering the inner space of the transverse cofferdam or without having to come from the discharge line which is not always easily accessible. The second end draws a gas sample. Furthermore, this allows gas to be drawn without operating the discharge valve and thus without interrupting its operation.

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

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

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

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 between 10 mm and 50 mm in thickness, preferably in the range between 15 mm and 20 mm in thickness Inside.

The specific characteristics of the indicated steel grades are described in the International Natural Gas Code.

By virtue 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 pair of transverse bulkheads.

According to one embodiment, the lateral dam comprises a thermal insulator.

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

According to one embodiment, the thermal insulation is located on one of the outer surfaces of the dam. According to one embodiment, the thermal insulation is located on the outer surface of one of the pair of transverse bulkheads.

According to one embodiment, the thermal insulation is located in the inner space of the transverse cofferdam, the thermal insulation is preferably attached to the longitudinal wall of the transverse cofferdam comprising the upper wall and a part of the inner hull .

By virtue of these features, the gas management device allows the thermal insulation to be maintained in a dry state. Therefore, the thermal insulation is not damaged by moisture or standing water. Thus, the thermal properties of the thermal insulation are optimally maintained.

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

According to one embodiment, the thermal insulation is a thermally insulating glass wool covered on an outer face by a thermally insulating metal foil or foam. Preferably, the thermal insulation is thermally insulating glass wool covered on an outer face by a metal foil, such as an aluminum layer. According to one embodiment, the thermally insulating foam is polyurethane foam (PUF).

According to one embodiment, the thermally insulating glass wool has a density in the range between 20 kg/m ³ and 60 kg/m ³ , preferably a density of 22 kg/m ³ .

According to one embodiment, the thermal insulation foam has a density in the range between 20 kg/m ³ and 80 kg/m ³ , preferably a density of 50 kg/m ³ .

By virtue of these features, heat losses are reduced and management of the gas atmosphere in the inner space of the transverse cofferdam is thus facilitated.

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

According to one embodiment, the thickness of the thermally insulating foam is in the range between 100 mm and 400 mm, preferably between 200 mm and 350 mm, for example 200 mm.

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

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

According to one embodiment, the second end of the dry air supply line occurs near a bottom wall of the transverse cofferdam.

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

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

By virtue of these features, the dry air supplied to the inner space of the transverse cofferdam allows more efficient discharge of the gas located in the inner space of the transverse cofferdam via the discharge line.

According to one embodiment, the dry air supply line and the gas discharge line are manufactured from steel or another material selected from the group consisting of stainless steel, D-grade, E-grade, DH-grade and/or EH-grade steel.

According to one embodiment, a water content in the inner space of the transverse cofferdam is kept below 25%, such as below 15%, and optimally below 5%. According to one embodiment, the water content in the inner space of the transverse cofferdam is close to 0%.

By virtue of these features, the development of frost on the thermal insulation or on the walls of the cofferdam is limited. Thus, the risk of degrading the thermal performance capability of the insulation or of corroding the cofferdam walls is substantially reduced.

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 a temperature between -25°C and -30°C.

According to one embodiment, the pressure sensor is a piezoresistive pressure sensor 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.

According to one embodiment, the pressure regulator is electronic.

According to one embodiment, the intake valve and/or the discharge valve are solenoid valves.

According to one embodiment, several intake valves are mounted in series on or branched from the dry air supply line. The intake valves can be different.

According to one embodiment, several discharge valves are mounted in series on or branched from the gas discharge line. These discharge valves can be different.

By virtue of these features, the gas management device of the ship is more adapted to the ship in which the gas management device is integrated. Furthermore, these features allow enhancing the safety, monitoring and ease of maintenance of the gas management equipment of the ship.

According to one embodiment, the dry air generator is a device for drying the atmosphere by heating.

According to one embodiment, the dry air generator is an appliance providing dry air with a dew point temperature below -40°C, preferably a dew point temperature of -45°C.

According to one embodiment, the dry air generator supplies dry air to the lateral cofferdam at a flow rate in the range between 10,000 m ³ /h and 20,000 m ³ /h (eg 15,000 m ³ /h) The inner space is filled with the transverse cofferdam with dry air.

According to one embodiment, the dry air generator supplies dry air into the inner space of the transverse cofferdam at a flow rate in the range between 50 m ³ /h and 500 m ³ /h to manage the transverse cofferdam The gaseous atmosphere in the inner space of the weir.

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

According to another embodiment, the gas management device for managing a gas atmosphere in the interior space of the transverse cofferdam comprises: a dry air supply line comprising a pipe located outside the transverse cofferdam and connected to a supply of dry air a first end of a first dry air generator, and a second end emerging in the inner space of the transverse cofferdam, wherein a first inlet valve is installed on the dry air supply line, the dry air a generator configured to deliver a dry air flow rate of greater than 10,000 m ³ /h (eg, between 10,000 m ³ /h and 20,000 m ³ /h) into the interior space of the cofferdam; a first Two dry air generators, which are connected to the dry air supply line branched from the first dry air generator, wherein a second air intake valve is installed between the second dry air generator and the dry air supply line , the second dry air generator configured to deliver a dry air flow rate of less than 1,000 m ³ /h (eg, between 50 m ³ /h and 500 m ³ /h) to the interior of the cofferdam in space.

Advantageously, the first dry air generator, the dry air supply line and the first inlet valve are components normally present in an LNG tanker. This embodiment is particularly advantageous since it limits the additional components to be installed on the ship.

According to one embodiment, the dry air generator is connected to the pressure regulator and the pressure regulator is further configured to: Emission of dry air from the dry air generator into the supply line is activated when the relative pressure in the interior space drops below the second threshold value, or in other words when the inlet valve is opened.

According to one embodiment, the present invention also provides a conveying system for a cold liquid product, the system comprising: the aforementioned ship; insulating pipes configured to connect the tank installed in the hull of the ship to a floating or onshore storage facility; and a pump for feeding a flow of the cold liquid product from the floating or onshore storage facility to the tank of the ship or from the tank of the ship to the tank through the insulating pipes The floating or onshore storage device.

According to one embodiment, the present invention also provides a method for loading or unloading such a ship, wherein a cold liquid product is routed from a floating or onshore storage facility to or from the tank of the ship through insulating pipes Routing to a floating or onshore storage facility.

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

Aspects of the invention are based on the idea of drying the inner space of the transverse cofferdam to allow a reduction of the temperature in the inner space of the transverse cofferdam without damaging the ship.

Such gas management equipment of a ship may be integrated via pipes and valves already present in the ship (eg already present in an LNG tanker). Furthermore, additional management or safety valves can be integrated into the vessel.

Figure 1 shows a graph representing the temperature variation T (°C) of a cofferdam as a function of time (t). Significant temperature fluctuations are common when a ship is sailing. In fact, when the ship includes full LNG tanks, a step 1 involves emptying seawater from the ship's ballast tanks and due to the heat flow from the tanks to the cofferdams, the temperature of the cofferdams adjacent to the cryogenic tanks drops significantly. According to a step 2, when the ship unloads or uses LNG, parts of the tanks are thus emptied and the ballast tanks are filled with seawater to optimize the voyage. Therefore, the temperature of the cofferdam varies through heat transfer from the seawater in the ballast tank to the cofferdam. In general, during step 2, the temperature in the cofferdam increases. Therefore, repeating steps 1 and 2, the ship completes the cycle. Therefore, it is difficult to regulate the temperature in the cofferdam.

FIG. 2 shows a ship 3 equipped with a LNG storage and transport equipment, comprising four sealed and thermally insulated compartments 4 . Each tank 4 is associated with a degassing mast 5 provided on the deck 12 of the ship 3 and which allows vapor phase gases to escape when there is excess pressure inside the associated tank 4 . An engine room 6 is provided at the stern of the ship 3 , this compartment generally includes a hybrid power supply steam turbine which can be operated by burning diesel or by burning boil-off gas from the cabin 4 . The tank 4 has a longitudinal dimension extending in the longitudinal direction of the ship 3 . Each tank 4 is bordered at each of its longitudinal ends by a pair of transverse bulkheads 7, 8 to delimit a sealed interstitial space (referred to by the term "cofferdam" 9). Thus, the compartments 4 are separated from each other by a transverse cofferdam 9 . It can be seen that the tanks 4 are each arranged in a load-carrying structure formed on the one hand by the double hull of the ship 3 and on the other hand by one of the transverse bulkheads 7, 8 of each of the cofferdams 9 bordering the tanks 4 inside the structure.

Ships according to embodiments of the present invention may include several types of tanks without being limited to one particular tank (eg, a membrane tank for storing liquefied gases). The boat 4 has a multilayer structure (not shown in the figures) comprising from the outside to the inside a secondary thermally insulating barrier against an insulating element of a load-bearing structure, a secondary sealing film against the secondary thermally insulating barrier, A primary thermal insulating barrier comprising insulating elements against the secondary sealing membrane and a primary sealing membrane intended to be in contact with the liquefied gas contained in the tank. The main sealing membrane delimits an inner space of the chamber 4 for receiving liquefied gas.

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

Figure 3 shows a cross-sectional and perspective view of a transverse cofferdam 19 in a catamaran comprising an outer hull 10 and an inner hull 15 according to one embodiment. The transverse cofferdam 19 comprises a pair of transverse bulkheads delimiting an inner space 13 of the transverse cofferdam 19 . Only one of the two transverse bulkheads 17 is shown in this FIG. 3 to show the inner space 13 of the transverse cofferdam 19 . The transverse cofferdam 19 further comprises an upper wall 37 closing the inner space 13 . As an example, the upper wall 37 may be a wall parallel to the upper deck 12 of the ship. A part of the inner hull 15 situated opposite the upper wall 37 delimits the bottom of the inner space of the transverse cofferdam 19 . The ship further comprises a ballast tank 41 located outside the transverse cofferdam 19 . The ballast tank 41 is formed by a bottom part of the space between the inner hull 15 and the outer hull 10 of the ship.

The transverse cofferdam 19 further comprises a reinforcing structure 14 intersecting the inner space 13 in a non-tight manner. The inner space 13 of the transverse cofferdam 19 may contain a heating system 16 for controlling the temperature of the transverse cofferdam 19 . The heating unit is formed by glycol or another heated antifreeze through one of the twisted lines through which it circulates.

Figure 4 shows an embodiment of a transverse dam 19 further comprising a thermal insulation 40 in the inner space 23 of the transverse dam. Thermal insulation 40 is attached to the longitudinal walls of the transverse cofferdam 29 comprising the upper wall 37 and part of the inner hull 15 . If the transverse cofferdam 19 is located between two compartments 4 , only the two transverse bulkheads 17 are not covered with thermal insulation 40 .

Figure 5 shows gas management equipment of a ship for managing a gas atmosphere in the interior space 23 of a transverse cofferdam 29 of a ship according to one embodiment. The transverse cofferdam 29 comprises a pair of transverse bulkheads 107, 109 delimiting the inner space 23 of the transverse cofferdam and an upper wall 37 closing the inner space. As in FIG. 4 , the transverse cofferdam 29 includes a thermal insulation 40 located in the interior space 23 of the transverse cofferdam, wherein the thermal insulation 40 is attached to the transverse cofferdam 29 comprising the upper wall 37 and a part of the inner hull 15 on the vertical wall. The ship's gas management equipment includes: A dry air supply line 30, which 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 a dry air generator 31 for supplying dry air, and emerges at the side of the cofferdam A second end in the interior space 23 of the transverse cofferdam 29 near the bottom portion of the inner hull 15 (that is, opposite the upper wall 37). The ship's gas management equipment further includes: an air inlet valve 32 mounted on the dry air supply line 30 outside the transverse cofferdam 29; a gas discharge line 33 passing through the upper wall 37 and comprising a first end emerging in the interior space 23 of the transverse cofferdam 29 and a second end emerging outside the ship; a discharge valve 34, located outside the transverse cofferdam 29, mounted on the gas discharge line 33; a pressure sensor 35 configured to detect a relative pressure in the interior space 23 of the transverse cofferdam 29; A pressure regulator 36 is located outside the transverse cofferdam 29 and is connected to the pressure sensor 35 , the intake valve 32 and the discharge valve 34 .

In this case, the pressure regulator 36 is configured to: When the relative pressure in the internal space 23 drops below the second threshold value, the intake valve 32 is opened, the second threshold value being a positive value, such as approximately 5 kPa; When the relative pressure in the interior space 23 rises above a first threshold (eg, approximately 15 kPa) above a second threshold, the discharge valve 34 is opened. Additionally, pressure regulator 36 may be configured to perform one or more of these actions: When the relative pressure in the inner space 23 rises above the first threshold value, or when it rises above a third threshold value in the range between the second threshold value and the first threshold value (with - hysteresis), close the intake valve 32; When the relative pressure in the inner space 23 drops below the second threshold value, or when it drops below a fourth threshold value in the range between the first threshold value and the second threshold value (with - hysteresis), close the discharge valve 34. Such a gas management device can be integrated, for example, to regulate the gas atmosphere of the cofferdams 9 and 19 shown above.

Figure 6 shows a gas management device for managing a gas atmosphere in the interior space 23 of the transverse cofferdam 29 according to another embodiment. As before, pressure regulator 136 is connected to pressure sensor 35 and intake valve 32 . This embodiment differs from FIG. 5 in that the discharge valve 134 is a mechanical open and close discharge valve 134 that is not connected to the pressure regulator 136 and that opens and closes automatically depending on the pressure present in the interior space 23 . The mechanically open and close discharge valve 134 is configured to open when a relative pressure in the interior space 23 rises above a first threshold value and to close again (optionally with a hysteresis) when it falls below this value. Accordingly, mechanically opening and closing the discharge valve 134 includes, for example, a spring closing mechanism or a flap closing mechanism. This mechanical opening and closing of the discharge valve 134 fulfills a safety function, since it prevents in particular damage which may be caused by excess pressure in the inner space 23 of the transverse cofferdam 29 .

The gas management device further includes a relief valve 18 . The discharge valve 18 is installed on the gas discharge line 33 outside the transverse cofferdam 29 and upstream of the mechanically open and closed discharge valve 134 . Therefore, a certain amount of gas can be extracted from the inner space 23 of the transverse cofferdam 29 to analyze the gas atmosphere or temperature of the inner space 23 of the transverse cofferdam 29 . Thus, the gaseous atmosphere in the inner space 23 of the transverse cofferdam 29 can be adjusted. The embodiments described via the figures are not limited to one particular type of lateral dam, for example, the embodiment described in Figure 6 may be applied to the dam described in one of the preceding figures.

The transverse cofferdam 29 comprises a thermal insulation 40 covering the inner surface of the longitudinal walls of the transverse cofferdam 29 over the entire perimeter of the interior space 23 , including the upper wall 37 and the inner hull 15 , as in FIG. 5 . In the embodiment shown in FIG. 6 , the transverse cofferdam 29 further comprises a thermal insulation 140 on the inner surface of the transverse wall 107 opposite the adjacent vessel 4 . In this embodiment, the thermal insulation 40 restricts heat flow with the ballast water and the surrounding air and the thermal insulation 140 further restricts heat flow with compartments adjacent to the transverse bulkhead 107, for example with the engine room 6 or with Heat flow from any other heat source at a temperature above the temperature of the ship 4.

Thermal insulation 40 or 140 may be glass wool covered on an outer surface with a vapor barrier such as a layer of aluminum. The glass wool can be attached by means of protruding spikes (not shown in the figures) having a first end welded to a wall of the transverse cofferdam 29 and passing through the glass wool. To hold the glass wool in place, a locking member, such as a clip, is added over the glass wool on a second end of the nail.

With respect to Figures 8 and 9, embodiments are described above in which the previously described gas management equipment is installed in other types of ships.

For example, in a tanker 80, as shown in a cross-sectional view in FIG. .

The oil has a temperature higher than that of the LNG in tank 4 . It is also possible to heat the oil by a heating device to increase its viscosity to facilitate its loading or unloading. For example, it may have a temperature of 60°C.

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

Similarly, the vessel 90 shown in Figure 9 is an LNG powered vessel. Ship 90 may be a container ship or a bulk carrier. A bulk carrier is a ship designed to transport solid bulk products. Thus, in a manner known per se, in front of its bridge 44 in a longitudinal direction X'-X of the ship 90, the ship 90 comprises one or more cargo holds 45 for transporting a solid bulk product. The cargo holds 45 are spaced apart in the longitudinal direction X'-X of the ship 90 in a manner known per se. It should be noted that only one of these cargo bays 45 , namely the cargo bay 45 closest to the bridge 44 , is shown schematically in FIG. 9 . Vessel 90 further comprises a sealed and thermally insulated tank 4 containing LNG intended to supply a propulsion system 46 . The cabin 4 is located behind the bridge 6 in the longitudinal direction X'-X. Tank 4 is separated from heat sources (ie bridge, propulsion system 46 and cargo tank 45 ) by a transverse cofferdam 49 . The transverse cofferdam 49 includes, inter alia, thermal insulation and gas management equipment as described above. Thus, like the ship described above, the heat flow between the heat source and the tank 4 is significantly restricted.

The gas management device described above can implement a method comprising one of the following steps: - When a relative pressure in the inner space of the cofferdam drops below 5 kPa, dry air is sent via a dry air generator supplying a dry air supply line into the inner space of the transverse cofferdam so that the cofferdam receives only dry air rather than moist ambient air; - When the relative pressure increases above 14 kPa, the gas is discharged from the inner space of the transverse cofferdam to the space outside the transverse cofferdam through the discharge pipeline. 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. The values shown in the figure can be adapted according to the desired gas management.

Referring to Fig. 7, a sectional view of an LNG tanker 70 shows a generally prismatic sealed and thermally insulated compartment 71 installed in the double hull 72 of the ship. The wall of the tank 71 includes a main sealing barrier intended to be in contact with the LNG contained in the tank, a secondary sealing barrier arranged between the main sealing barrier of the ship and the double hull 72, and a secondary sealing barrier respectively arranged between the main sealing barrier and the secondary Two insulating barriers between the barriers and between this secondary sealing barrier and the double hull 72 are to be sealed.

In a manner known per se, the loading/unloading pipe 73 placed on the upper deck of the ship can be connected by suitable connectors to a marine or seaport terminal for transferring a LNG cargo from or to the tank 71 .

FIG. 7 shows an example of a marine terminal comprising a loading station 75 , a subsea pipeline 76 and an onshore facility 77 . The loading station 75 is a fixed offshore installation comprising a movable arm 74 and a tower 78 supporting the movable arm 74 . The movable arm 74 supports a bundle of insulating flexible tubes 79 connectable to the loading/unloading tube 73 . The orientable movable arm 74 is suitable for all types of LNG tanker gauges. A connecting line not shown in the figure extends to the interior of column 78 . Loading station 75 allows LNG tanker 70 to be loaded from or unloaded to onshore facility 77 . This equipment includes a liquefied gas storage tank 80 and a connecting pipeline 81 connected to the loading and unloading station 75 by the submarine pipeline 76 . Subsea pipeline 76 allows liquefied gas to be transported a significant distance (eg 5 km) between loading station 75 and onshore facility 77, which allows LNG tanker 70 to maintain a significant distance from shore during loading operations.

In order to generate the pressure required to transfer the liquefied gas, a pump on board the ship 70 and/or a pump provided on the shore facility 77 and/or a pump provided on the loading station 75 is implemented.

Although the invention has been described with reference to a number of specific embodiments, it is clear that the invention is in no way restricted thereto and it includes all technical equivalents of the described means, if they fall within the scope of the invention, and combinations thereof.

Gas management equipment for managing a gas atmosphere in the interior space of a transverse cofferdam may, for example, further comprise branch lines with manual valves across, for example, inlet valves or discharge valves, or even links to pressure sensing Alarm systems (PAL, PAH, PALL, PAHH) for detectors without departing from the scope of the present invention.

Some elements, in particular components of the pressure regulator, can be produced in various forms by hardware and/or software components in a unitary or distributed manner. The hardware components that can be used are 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.

Use of the verb "to comprise" or "to comprise" and its conjugations does not exclude the presence of elements or steps other than those described in a claim.

In the scope of the patent application, any reference symbols between brackets shall not be interpreted as limiting the scope of the patent application.

1: step 2: step 3: boat 4: Sealed and thermally insulated cabin 5: Degassing the mast 6:Engine room 7: Transverse bulkhead 8: Transverse bulkhead 9: Horizontal cofferdam 10: External Hull 12: Upper deck 13: Internal space 14: Strengthen the structure 15: Internal Hull 16: Heating system 17: Transverse bulkhead 18: Relief valve 19: Horizontal cofferdam 23: Internal space 29: Horizontal cofferdam 30: Dry air supply line 31: Dry air generator 32: intake valve 33: Gas discharge line 34: Drain valve 35: Pressure sensor 36: Pressure regulator 37: upper wall 39: Horizontal cofferdam 40: thermal insulation 41: ballast tank 42: Cargo tank 43: heat flow 44: bridge 45: cargo hold 46: Propulsion system 49: Horizontal cofferdam 70: LNG tanker 71: Sealed and thermally insulated cabin 72: double hull 73: Loading/unloading tube 74: movable arm 75: loading and unloading station 76: Submarine pipeline 77:shore equipment 78: tower 79: Insulated flexible pipe 80: tanker/ship/liquefied gas storage tank 81: Connect the pipeline 90: boat 107: Transverse bulkhead 109: Transverse bulkhead 134: discharge valve 136: Pressure regulator 140: thermal insulation

The invention will be better understood and further objects, details, features and advantages thereof will become more apparent in the following description of some specific embodiments of the invention, provided by way of a non-limiting illustration only, with reference to the accompanying drawings .

Figure 1 shows typical temperature variations of a cofferdam of an LNG carrier as a function of time during operation. Figure 1 is a diagram which does not form part of the invention but is useful for understanding.

Figure 2 is a cross-sectional view along a longitudinal axis of an LNG carrier according to one embodiment.

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

4 is a cross-sectional view of a transverse cofferdam that may be used in the ship of FIG. 2 , including a thermal insulation, according to one embodiment.

FIG. 5 is a schematic diagram showing a transverse cofferdam in a ship of FIG. 2 with a gas management device for managing a gas atmosphere in the interior space of the transverse cofferdam in a ship according to one embodiment.

Fig. 6 is a schematic diagram showing a transverse cofferdam in a ship of Fig. 2 with a gas management device for managing a gas atmosphere in the interior space of the transverse cofferdam in a ship according to another embodiment.

Figure 7 is a schematic cross-sectional view of an LNG tanker including a tank and a terminal for loading/unloading the tank, according to one embodiment.

Figure 8 shows a schematic sectional view of a tanker in a transverse direction.

Figure 9 is a 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 aft of the bridge of the ship in the longitudinal direction of the ship.

3: boat

4: Sealed and thermally insulated cabin

5: Degassing the mast

6:Engine room

7: Transverse bulkhead

8: Transverse bulkhead

9: Horizontal cofferdam

10: External Hull

12: Upper deck

Claims (16)

A ship (3, 70) for transporting a cold fluid, the ship (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 or each 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 enclosing the interior space (13,23) one upper wall (37); at least one airtight and thermally insulated compartment (4, 71) arranged in a section 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 comprises: A dry air supply line (30) comprising a first end located outside the transverse cofferdam (9, 19, 29) and connected to a dry air generator (31) supplying dry air, and emerging from the transverse A second end in the inner space (13, 23) of the cofferdam (9, 19, 29); an air inlet valve (32), which is installed on the dry air supply line (30); A gas discharge line (33) comprising a first end emerging in the interior space (13, 23) of the transverse cofferdam (9, 19, 29) and a first end emerging outside the vessel (3, 70) a second end; a discharge valve (34, 134) mounted on the gas discharge line (33), the discharge valve (34, 134) configured so that when a relative pressure in the interior space (13, 23) rises to a Open when above the first threshold; a pressure sensor (35) configured to detect a relative pressure in the inner 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) configured to: When the relative pressure in the internal space (13, 23) drops below a second threshold value, the intake valve (32) is opened, the second threshold value being lower than the first threshold value A positive value. The ship of claim 1, wherein the pressure regulator (36, 136) is further configured to: When the pressure in the inner space (13, 23) rises above a third threshold value in the range between the second threshold value and the first threshold value, the intake valve (32) is closed . The ship of claim 2, wherein a difference between the third threshold and the second threshold is less than 2 kPa (20 mbarg). The ship of any one of claims 1 to 3, wherein the pressure regulator (136) is further connected to the discharge valve (34, 134), the pressure regulator (136) is further configured to: When the pressure in the inner space (13, 23) rises above the first threshold value, the discharge valve (34, 134) is opened. As the ship of claim 4, wherein the pressure regulator (36) is further configured to: The discharge valve (34) is closed when the pressure in the inner space (13, 23) drops below a fourth threshold value in the range between the first threshold value and the second threshold value. The ship of claim 5, wherein a difference between the fourth threshold and the first threshold is less than 2 kPa (20 mbarg). The ship according to any one of claims 1 to 3, wherein the discharge valve (34, 134) is a mechanically open and close discharge valve (34, 134) configured to: Opens when a relative pressure in one of the interior spaces (13, 23) rises above the first threshold value. A ship according to any one of claims 1 to 7, wherein the second threshold is between 1 kPa (10 mbarg) and 10 kPa (100 mbarg), preferably between 2 kPa (20 mbarg) and 5 kPa (50 mbarg). A ship according to any one of claims 1 to 8, wherein the first threshold is between 12 kPa (120 mbarg) and 18 kPa (180 mbarg), preferably between 13 kPa (130 mbarg) and 15 kPa (150 mbarg). The ship according to any one of claims 1 to 9, wherein the gas management device further comprises a gas discharge valve (18), the gas discharge valve (18) is installed on the discharge valve (34, 134) upstream Gas discharge line (33) to allow extraction of a volume of gas from the inner space (13, 23) of the transverse cofferdam. The ship according to any one of claims 1 to 10, wherein the pair of transverse bulkheads (7, 8, 17, 107, 109) are manufactured from a steel grade selected from D grade, E grade, DH grade and EH grade. The ship according to any one of claims 1 to 11, wherein the transverse cofferdam (9, 19, 29) comprises a thermal insulation (40) located in the inner space (13, 23) of the transverse cofferdam, The thermal insulation (40) is preferably attached to the longitudinal wall of the transverse cofferdam (9, 19, 29) comprising the upper wall (37) and part of the inner hull (15). The ship according to any one of claims 1 to 12, wherein the transverse cofferdam (9, 19, 29) comprises a thermal insulator on an outer surface of the cofferdam. The ship as claimed in claim 12 or 13, wherein the heat insulation (40) is a heat insulating glass wool covered by a metal foil on an outer surface. A conveying system for a cold liquid product, the system comprising: a ship (3, 70) according to any one of claims 1 to 14; insulating pipes (73, 79, 76, 81), which are configured to connecting the tank (4, 71) installed in the hull (110) of the ship to a floating or onshore storage facility (77); and a pump for passing the cold liquid product through the insulating pipes A flow is fed from the floating or onshore storage facility to the tank of the ship or from the tank of the ship to the floating or onshore storage facility. A method for loading or unloading a ship (3, 70) according to any one of claims 1 to 15, wherein a cold liquid product passes through insulating pipes (73, 79, 76, 81) from a floating or onshore storage facility (77) Routing to the tank (4, 71 ) of the vessel (3, 70) or from the tank (4, 71 ) to a floating or onshore storage facility (77).

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