Ship comprising liquefied gas storage tank, and operating method of ship

Abstract

The present invention relates to a ship comprising a liquefied gas storage tank, and an operating method of the ship. According to the present invention, the loading capacity of liquefied gas of the ship can be additionally ensured, various courses can be sailed, and sailing distance is increased such that sailing efficiency can be significantly increased. The ship comprising the liquefied gas storage tank, according to the present invention, comprises: one or more storage tanks, which are provided below a deck and store LNG; and one or more multi-tanks, which are provided on the deck of the ship and store LNG for multiple purposes.

Description

Vessels containing liquefied gas storage tanks and methods of operating vessels

[0001] The present invention relates to a vessel including a liquefied gas storage tank and a method for operating the vessel. According to the present invention, the vessel can additionally secure the liquefied gas loading capacity, operate on various routes, and increase the operating distance, thereby dramatically improving operating efficiency.

[0002] As environmental pollution regulations become more stringent, demand for gaseous fuels, such as natural gas, is increasing, replacing gasoline and diesel as the primary fuel. Natural gas can be transported in gaseous form through onshore or offshore pipelines, or stored in liquid form onboard carriers for transport to distant demand locations.

[0003] Liquefied natural gas (LNG) is a colorless, odorless liquid obtained by cooling methane-based natural gas to approximately -162°C, liquefying it. Liquid natural gas has approximately 1 / 600th the volume of its gaseous form. Therefore, for demand sites located far from the source, it is advantageous to transport LNG in cryogenically liquefied form via LNG carriers.

[0004] Vessels that store liquefied gas, such as liquefied gas carriers that sail the sea carrying liquefied gas and unload it at the point of demand, or LNG RVs (Regasification Vessels) that sail the sea carrying LNG and, upon arriving at the point of demand, regasify the stored LNG and unload it as natural gas, are equipped with liquefied gas storage tanks to store the liquefied gas in an extremely low-temperature liquid state.

[0005] Natural gas supply and demand sources are spread across the globe, so if a ship can transport natural gas shipped from each supply source to each demand source at low cost and in large quantities at once, the ship will have very high value.

[0006] In cases where the distance between the supplier and the demand is short, natural gas can be transported in gaseous form using pipelines. Therefore, liquefied gas carriers are generally designed to transport large quantities of liquefied gas over long distances from the supplier to the demand, and are not optimized for transporting relatively small quantities of liquefied gas over short routes.

[0007] The transport mechanism of a liquefied gas carrier is to load liquefied gas into a liquefied gas storage tank provided on a liquefied gas carrier from a liquefied gas supplier, move the liquefied gas carrier loaded with liquefied gas in the liquefied gas storage tank by sailing at sea to a liquefied gas demander, then anchor at a terminal and unload the liquefied gas loaded in the liquefied gas storage tank to the liquefied gas demander.

[0008] When a liquefied gas carrier moves from a supplier to a consumer after loading liquefied gas through this process, the operational efficiency of the carrier can be improved if the maximum amount of liquefied gas can be loaded.

[0009] Additionally, if a liquefied gas carrier can reach multiple demand points during a single operation cycle, i.e., if the operating distance can be increased, the operating efficiency of the carrier can be dramatically improved.

[0010] The present invention aims to provide a vessel including a liquefied gas storage tank, which can significantly increase operating efficiency by securing additional liquefied gas loading capacity of the vessel and increasing the operating distance by enabling operation on various routes, and a method for operating the vessel.

[0011] The problems addressed by the present invention are not limited to those mentioned above. Other technical problems not mentioned will be readily apparent to those skilled in the art, as described below.

[0012] According to one aspect of the present invention for achieving the above-described object, a ship including a liquefied gas storage tank is provided, including one or more storage tanks provided under a deck and storing LNG; and one or more multi-tanks provided on an upper deck of the ship and storing LNG for multiple purposes.

[0013] Preferably, the LNG stored in the multi-tank can be used for one or more of the following purposes: cargo, fuel, maintenance of the storage tank, and maintenance of the pressure or temperature of the storage tank.

[0014] Preferably, the operating pressure of the multi-tank may be higher than the operating pressure of the storage tank.

[0015] Preferably, the multi-tank may be placed on the stern side or adjacent to the engine room on the bow side.

[0016] Preferably, the vessel may further include a loading manifold for connecting an LNG supplier and a vessel to receive LNG; a first loading line connected from the loading manifold to the multi-tank; and a second loading line connected from the loading manifold to the storage tank.

[0017] Preferably, the multi-tank and the storage tank may be connected, and a first charging line for supplying LNG from the multi-tank to the storage tank may be further included.

[0018] Preferably, the engine further comprises: an engine; and a fuel supply unit for supplying LNG as fuel from the storage tank to the engine; and LNG transferred to the storage tank through the first charging line can be supplied from the storage tank to the engine through the fuel supply unit.

[0019] Preferably, the storage tank may further include: an injection nozzle provided in the upper space and supplying LNG by injection to cool the upper space; an injection line for transporting LNG to be injected through the injection nozzle; and an injection branch line connecting the multi-tank and the injection line and for injecting LNG from the multi-tank to the storage tank through the injection line.

[0020] Preferably, the engine further comprises: an engine; and a fuel supply unit for supplying LNG as fuel from the storage tank to the engine; and LNG transferred from the multi-tank to the storage tank through the injection branch line can be supplied from the storage tank to the engine through the fuel supply unit.

[0021] Preferably, the system may further include a compressor for compressing gas discharged from the storage tank; and an evaporation gas branch line connecting the compressor and the multi-tank and supplying the gas compressed by the compressor to the multi-tank.

[0022] Preferably, the tank may further include a re-liquefaction device that re-liquefies the evaporation gas generated by natural vaporization of LNG stored in the storage tank to generate re-liquefied evaporation gas; and a re-liquefaction branch line that recovers the re-liquefied evaporation gas generated in the re-liquefaction device to the multi-tank.

[0023] According to another aspect of the present invention for achieving the above-described object, there is provided a method for operating a ship including at least one storage tank provided under a deck and storing LNG; and at least one multi-tank provided on an upper deck of the ship and storing LNG for multiple purposes; the method comprising: loading LNG from an LNG supplier into at least one of the storage tank and the multi-tank;

[0024] Preferably, the method may further include a step of transporting LNG loaded in the multi-tank to the storage tank in a liquid state.

[0025] Preferably, the temperature of the storage tank can be lowered by further including a step of supplying LNG loaded in the multi-tank by spraying it into the storage tank.

[0026] Preferably, the LNG supplied by injection from the multi-tank to the storage tank is in a gaseous state, and the step of supplying the gas as fuel for the ship may be further included.

[0027] Preferably, the method may further include a step of supplying LNG supplied from the multi-tank to the storage tank to a fuel supply unit; and a step of vaporizing the LNG supplied to the fuel supply unit and supplying it as fuel for the engine.

[0028] Preferably, the method may further include a step of measuring the pressure of the multi-tank; and a step of increasing the pressure of the multi-tank by supplying the evaporation gas generated by natural vaporization of LNG stored in the storage tank to the multi-tank when the measured pressure of the multi-tank is lower than a reference value.

[0029] Preferably, the method may further include a step of maintaining the operating pressure of the multi-tank higher than the operating pressure of the storage tank; a step of re-liquefying the evaporation gas generated by natural vaporization of LNG stored in the storage tank to generate re-liquefied evaporation gas; and a step of recovering the re-liquefied evaporation gas to the multi-tank.

[0030] Preferably, the method may further include a step of unloading LNG stored in the storage tank to a first demand source; and a step of moving LNG stored in the multi-tank to a second demand source using it as fuel.

[0031] Preferably, the ship may further include a step of supplying LNG stored in the multi-tank to the storage tank to cool down the storage tank before the ship arrives at the destination.

[0032] A vessel including a liquefied gas storage tank according to the present invention and a method for operating the vessel can drastically improve the operating efficiency of the vessel by providing a multi-tank, which is a multi-purpose supplementary tank installed on the upper deck.

[0033] In particular, since the liquefied gas stored in the multi-tank can be unloaded as cargo together with the liquefied gas stored in the liquefied gas storage tank upon arrival at the point of demand, the liquefied gas cargo capacity of the carrier can be additionally secured, thereby increasing freight profits.

[0034] In addition, since additional cargo capacity is secured, the operating distance of the carrier can be increased, and it can be operated on various routes, including long-distance and short-distance routes, thereby securing flexibility in ship operation and cargo transportation depending on the cargo volume, location of demand, route, and operating distance.

[0035] In addition, the liquefied gas stored in the liquefied gas storage tank can be unloaded to the demand location, and even after unloading, the liquefied gas stored in the multi-tank can be used as fuel to sail to the next destination.

[0036] Additionally, cool-down of storage tanks and pipes can be performed in advance while the ship is in operation, reducing terminal berthing time and terminal usage costs.

[0037] Additionally, it is compatible with existing liquefied gas carriers while minimizing design changes or additions to existing equipment of the carrier, such as fuel supply devices.

[0038] In addition, the present invention can be applied to all types of ships equipped with a liquefied gas storage tank, as well as liquefied gas carriers.

[0039] The present invention can be applied to newly built vessels, existing vessels, and even retrofitted vessels. Specifically, by installing a multi-tank on an existing vessel and connecting it to related equipment, such as a fuel supply system and cargo handling system already installed on the vessel, the vessel can be retrofitted with minimal modifications.

[0040] The effects of the present invention are not limited to those described above. Other effects not mentioned will be readily apparent to those skilled in the art from this specification and the accompanying drawings.

[0041] Figure 1 is a conceptual diagram briefly illustrating the configuration of a ship according to one embodiment of the present invention.

[0042] Figures 2 and 3 are schematic plan views illustrating a portion of a vessel according to one embodiment of the present invention.

[0043] FIG. 4 is a side view schematically illustrating a portion of a vessel according to one embodiment of the present invention.

[0044] In order to fully understand the operational advantages of the present invention and the objects achieved by the embodiments of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

[0045] Hereinafter, the configuration and operation of preferred embodiments of the present invention will be described in detail with reference to the attached drawings. When adding reference numerals to components in each drawing, it should be noted that, as much as possible, identical components are indicated with the same numerals even if they are shown in different drawings. In addition, the following embodiments may be modified in various different forms, and the scope of the present invention is not limited to the following embodiments.

[0046] A vessel including a liquefied gas storage tank according to the present invention is a vessel equipped with one or more liquefied gas storage tanks, and may include vessels with self-propulsion capabilities such as LNG carriers, LNG RVs (Regasification Vessels), and bunker vessels, as well as offshore structures that do not have propulsion capabilities but float on the sea, such as LNG FPSOs (Floating Production Storage Offloading) and LNG FSRUs (Floating Storage Regasification Units).

[0047] In the embodiments of the present invention described below, the ship is a ship that transports liquefied gas as cargo, and an example of a liquefied gas carrier will be described.

[0048] In addition, the liquefied gas here may be a liquefied gas that can be transported by liquefying gas at a low temperature, and may be, for example, a hydrocarbon-based liquefied gas such as LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), liquefied ethylene gas, liquefied propylene gas, liquefied methanol, liquefied ethanol, or bio-oil. Alternatively, it may be a non-hydrocarbon-based liquefied gas such as liquefied carbon dioxide, liquefied hydrogen, or liquefied ammonia.

[0049] In the embodiments of the present invention described below, the liquefied gas will be described as LNG as an example.

[0050]

[0051] Hereinafter, with reference to FIGS. 1 to 4, a vessel including a liquefied gas storage tank according to embodiments of the present invention and a method of operating such a vessel will be described.

[0052] A vessel (hereinafter referred to as a “vessel”) containing liquefied gas according to one embodiment of the present invention may include one or more storage tanks (100) installed on the lower deck of the vessel and storing LNG, and one or more multi-tanks (200) installed exposed on the upper deck of the vessel and storing LNG for multiple purposes.

[0053] In this embodiment, at least one multi-tank (200) can be provided depending on the purpose of using the multi-tank (200), and its capacity can also be determined depending on the purpose of use.

[0054] In this embodiment, the storage tank (100) is a cargo hold with added insulation function located under the deck, i.e., inside the hull, and can control pressure and temperature as much as possible so that LNG can be maintained in a liquid state while being stored. The operating pressure of the storage tank (100) of this embodiment may be about 1 to 1.7 bara, or about 1 to 1.35 bara, and the operating temperature may be about -150 to -163°C.

[0055] In addition, the multi-tank (200) of the present embodiment can be controlled to have its operating pressure higher than atmospheric pressure so that LNG can be maintained in a liquid state as much as possible while it is stored, even though it is a tank exposed to the upper part of the deck.

[0056] In addition, the operating pressure of the multi-tank (200) may be higher than the operating pressure of the storage tank (100) so that LNG can be transferred from the multi-tank (200) to the storage tank (100) by its own pressure difference without using a separate pressurizing means.

[0057] In this embodiment, the operating pressure of the multitank (200) may be about 4 to 8 barg, and the operating temperature may be about -130 to -150°C, or about -140°C.

[0058] The multi-tank (200) of the present embodiment may be an IMO Type C tank as a pressurized vessel.

[0059] Additionally, the multi-tank (200) of the present embodiment may be installed on the upper part of the stern or bow side deck.

[0060] An engine room (ER) in which the ship's engine (400) is installed is arranged on the lower deck of the stern side of the ship according to the present embodiment, and an accommodation area (AA) including a cabin (accommodation) and a wheelhouse (wheelhouse), which are living spaces for the crew, is arranged on the upper deck above the engine room (ER).

[0061] Because the stern, where the engine room (ER) and accommodations (AA) are typically located, is heavier than the bow, additional ballast tanks (not shown) are required on the bow to maintain balance. These ballast tanks are filled with seawater and serve to maintain the vessel's balance by controlling the water level.

[0062] When the multi-tank (200) according to the present embodiment is placed on the bow side, the multi-tank (200) has the effect of replacing the role of the ballast tank on the bow side.

[0063] If the multi-tank (200) is placed on the upper deck of the bow side, the length of the piping and cables connecting it to the cargo compressor room (CR) and the engine room (ER) may be long, which may be disadvantageous in terms of installation cost and thermal efficiency. However, there is no need to secure an additional ballast tank on the bow side, and rather, some ballast tanks can be omitted or the capacity of the ballast tanks can be reduced compared to existing ships. In addition, since the capacity of the ballast tanks can be reduced or some of the ballast tanks can be omitted, free space within the hull is secured, and since an additional storage tank (100) can be placed in the secured space or the capacity of the storage tank (100) can be increased, there is an advantage in that additional cargo space can be secured within the hull.

[0064] Meanwhile, in this embodiment, the space under the deck, i.e., the space inside the hull, which extends from the front of the engine room (ER) to the bow and is equipped with a storage tank (100), is referred to as a cargo area.

[0065] On the upper deck of the cargo area, especially on the upper deck of the storage tank (100) among the multiple storage tanks (100) arranged adjacent to the engine room (ER), a cargo compressor room (CR) is arranged in which a fuel supply unit is installed to process LNG stored in the storage tank (100) and supply it as fuel for an engine (400) arranged in the engine room (ER).

[0066] When the multi-tank (200) according to the present embodiment is installed on the stern side, the multi-tank (200) can be placed so as to satisfy at least one condition among the upper deck adjacent to the engine room (ER), the upper deck in front of the living quarters (AA), and the upper deck adjacent to the cargo compressor room (CR).

[0067] Typically, the cargo compressor room (CR) is located on the upper deck adjacent to the engine room (ER) located on the lower deck to maximize the fuel supply efficiency from the cargo compressor room (CR) to the engine room (ER).

[0068] When the multi-tank (200) according to the present embodiment is installed on the stern side, the multi-tank (200) may be installed adjacent to the engine room (ER), more specifically, adjacent to the position where the engine room (ER) is installed on the lower deck, and on the upper deck adjacent to the cargo compressor room (CR).

[0069] The drawing illustrates an example where the multitank (200) is placed on the port side relative to the cargo compressor room (CR), but is not limited thereto.

[0070] When the multi-tank (200) is placed on the upper part of the stern deck, the length of the pipes and cables connecting the multi-tank (200) to the cargo compressor room (CR) and the engine room (ER) is shortened, so compared to the case where it is placed on the upper part of the bow deck, unnecessary heat ingress is reduced, installation cost (CAPEX) can be reduced, and there is the advantage of ease of operation.

[0071] Additionally, the multi-tank (200) can be arranged longitudinally (in the direction of the length of the ship) or transversely (in the direction of the width of the ship) on the deck.

[0072] FIG. 2 illustrates an example in which one side of a multi-tank (200) is positioned longitudinally relative to the bow, with one side facing the bow and the other side facing the stern. In this way, one or more multi-tanks (200) may be provided longitudinally.

[0073] In addition, FIG. 3 illustrates an example in which one side of the multi-tank (200) faces port side and the other side faces starboard side, and is arranged transversely with respect to the bow. In this way, one or more multi-tanks (200) may be provided transversely.

[0074] Additionally, when multiple multi-tanks (200) are provided, some may be arranged longitudinally and some may be arranged transversely.

[0075] A vessel according to one embodiment of the present invention may include a loading manifold (not shown) for connection to an LNG supplier when receiving LNG from an LNG supplier, such as an LNG terminal, a land-based LNG supply vessel, an LNG bunkering vessel, an LNG FPSO, or a vessel supplying LNG.

[0076] The vessel according to the present embodiment may further include at least one of a first loading line (LL1) connected from the loading manifold to the multitank (200) and a second loading line (LL2) connected from the loading manifold to the storage tank (100).

[0077] A first loading valve (LV1) may be provided in the first loading line (LL1), and a second loading valve (LV2) may be provided in the second loading line (LL2). By controlling the first loading valve (LV1) and the second loading valve (LV2), the flow of fluid through each line may be controlled.

[0078] The first loading line (LL1) and the second loading line (LL2) may be provided independently connected to the loading manifold, or at least one of the first loading line (LL1) and the second loading line (LL2) may be provided by branching from one loading line connected from the loading manifold.

[0079] In addition, a vessel according to one embodiment of the present invention may further include a second charging line (FL2) for supplying LNG from a storage tank (100) to a multitank (200).

[0080] The second charging line (FL2) may be equipped with a second charging valve (FV2), and by controlling the second charging valve (FV2), the flow of LNG through the second charging line (FL2) may be controlled.

[0081] By providing a second charging line (FL2), LNG stored in the storage tank (100) can be transferred to the multi-tank (200).

[0082] The storage tank (100) may be equipped with one or more pumps for discharging LNG stored in the storage tank (100) from the storage tank (100) and transporting it to the outside. Here, the one or more pumps equipped in the storage tank (100) may include, depending on their purpose, one or more of a cargo pump (not shown) for unloading LNG to a demander, a fuel pump (310) for supplying LNG as fuel for an engine, and a stripping pump (or spray pump) (not shown) for supplying LNG to an injection line (SL).

[0083] LNG stored in the storage tank (100) can be introduced into the second charging line (FL2) by one or more of a cargo pump, a fuel pump (310), and a stripping pump, and the LNG introduced into the second charging line (FL2) can be transported to the multi-tank (200) and stored in the multi-tank (200).

[0084] In addition, a vessel according to one embodiment of the present invention may further include a first charging line (FL1) connecting a multi-tank (200) provided on the upper deck and a storage tank (100) or multi-tank (200) provided on the lower deck and a second loading line (LL2).

[0085] The first charging line (FL1) may be equipped with a first charging valve (FV1), and by controlling the first charging valve (FV1), the flow of fluid through the first charging line (FL1) may be controlled.

[0086] By providing the first charging line (FL1), LNG stored in the multi-tank (200) can be transferred to the storage tank (100).

[0087] As shown in the drawing, when the first charging line (FL1) is connected to the second loading line (LL2) that connects the loading manifold to the storage tank (100), LNG can be transferred from the multitank (200) to the storage tank (100) through the first charging line (FL1) and the second loading line (LL2).

[0088] By connecting the first charging line (FL1) to the second loading line (LL2) in correspondence with the line connecting the loading manifold to the storage tank on an existing ship, it will be possible to provide a modified ship by applying embodiments according to the present invention without significantly changing the structure or design of the existing ship.

[0089] Although not shown in the drawing, if the first charging line (FL1) is directly connected from the multi-tank (200) to the storage tank (100), LNG can be transported from the multi-tank (200) to the storage tank (100) through the first charging line (FL1), and the first charging line (FL1) and the second loading line (LL2) can be operated independently.

[0090] According to this embodiment, LNG stored in the multi-tank (200) can be transferred to the storage tank (100) using the first charging line (FL1), so LNG stored in the multi-tank (200) can also be unloaded to a demand location.

[0091] In addition, even if all of the LNG stored in the storage tank (100) is unloaded to the demand location, since LNG is stored in the multi-tank (200), the LNG stored in the multi-tank (200) can be used as fuel to move to another destination.

[0092] Additionally, the cool-down stage of the storage tank (100) can be performed in advance using LNG stored in the multi-tank (200) while the ship is in motion, without anchoring at the destination.

[0093] Here, the cool-down step of the storage tank (100) may be included in a series of processes performed before or after performing maintenance on the storage tank (100), or before loading LNG into the storage tank (100) after completing maintenance.

[0094] Even if the maintenance process of the storage tank (100) for storing ultra-low temperature liquefied gas is not specifically described, it can be carried out by performing known processes.

[0095] The maintenance process of the storage tank (100) may include a stripping step of emptying the LNG remaining in the storage tank (100) using a cargo pump or a stripping pump, a warming step of supplying warm gas to the storage tank (100) that has completed the stripping step to vaporize the LNG remaining in the reservoir, an inerting step of supplying an inert gas to the storage tank (100) that has completed the warming step to replace the gas in a gaseous state remaining in the storage tank (100), an aeration step of replacing the inert gas remaining in the storage tank (100) that has completed the inerting step with oxygen, and a step of performing maintenance of the storage tank (100) by having crew members enter the storage tank (100) that has been replaced with oxygen.

[0096] In addition, before loading LNG into the storage tank (100) after completing maintenance, the method may include a drying step for drying the inside of the storage tank (100) with dry air to remove moisture remaining in the storage tank (100), an inerting step for supplying an inert gas into the inside of the storage tank (100) to prevent explosion, a gassing-up step (or purging step) for supplying gaseous LNG, i.e., natural gas, to replace the storage tank (100) that has completed the inerting step, and a cool-down step for cooling the temperature of the storage tank (100) that has completed the gassing-up step to a temperature below a certain temperature.

[0097] Meanwhile, the operating pressure of the multi-tank (200) is higher than the operating pressure of the storage tank (100), and since the multi-tank (200) is placed on the upper part of the deck and the storage tank (100) is placed on the lower part of the deck, LNG can be transferred from the multi-tank (200) to the storage tank (100) through the first filling line (FL1) by gravity.

[0098] At the bottom of the multi-tank (200), a non-pressurized line (NL) may be further provided to discharge LNG from the multi-tank (200) without using a pressurizing means such as a pump and supply it to a storage tank (100) or other device.

[0099] By providing a non-pressurized line (NL), LNG stored in a multi-tank (200) can be supplied to a storage tank (100) or other devices without using a pressurizing means.

[0100] The non-pressurized line (NL) may be equipped with a non-pressurized valve (NV), and by controlling the non-pressurized valve (NV), the flow of fluid through the non-pressurized line (NL) can be regulated.

[0101] In this embodiment, an example is described in which a non-pressurized line (NL) is connected from a multi-tank (200) to a first filling line (FL1), and LNG discharged from the multi-tank (200) by its own gravity without using a pressurizing means is transferred to a storage tank (100) through the non-pressurized line (NL) and the first filling line (FL1).

[0102] However, this is not limited to this, and the non-pressurized line (NL) may be provided independently from the first filling line (FL1).

[0103] Alternatively, a supply pump (210) for discharging LNG from the multi-tank (200) may be further included so that the LNG stored in the multi-tank (200) can be transferred to the storage tank (100) through the first charging line (FL1).

[0104] Here, at least one supply pump (210) may be provided in one or more places, either inside or outside the multi-tank (200).

[0105] In addition, the supply pump (210) may be at least one of a fixed pump that is fixedly installed on the outside or inside of the multitank (200) or a retractable pump that can be moved as a foldable pump.

[0106] When the supply pump (210) is equipped as a fixed pump, at least two supply pumps (210) may be equipped. At least one of the two or more supply pumps (210) may be placed on standby, and when the other supply pump is unavailable, the supply pump (210) placed on standby may be used to discharge LNG from the multi-tank (200). In other words, at least one supply pump (210) may be used for redundancy purposes.

[0107] In the case where the supply pump (210) is equipped as a retractable pump, one supply pump (210) can be equipped per one multi-tank (200) or one supply pump (210) can be equipped per one or more multi-tanks (200), and thus, costs can be reduced compared to the case where the supply pump is equipped as a semi-submersible pump.

[0108] Meanwhile, according to the present embodiment, the storage tank (100) may further include an injection nozzle (not given a drawing symbol) for cooling the upper space by the heat of vaporization by spraying and vaporizing LNG, and an injection line (SL) for transporting LNG to be sprayed through the injection nozzle.

[0109] The injection line (SL) may be equipped with an injection valve (SV), and by controlling the injection valve (SV), the flow of fluid through the injection line (SL) can be controlled.

[0110] Although not shown in the drawing, a stripping pump (not shown) may be further included to supply LNG stored in the storage tank (100) to the injection line (SL). At this time, one side of the injection line (SL) may be connected to a plurality of injection nozzles, and the other side of the injection line (SL) may be connected to the stripping pump.

[0111] According to the present embodiment, the multi-tank (200) may further include an injection branch line (CL1) connecting the first charging line (FL1) or the second loading line (LL2) and the injection line (SL).

[0112] By providing an injection branch line (CL1), LNG transferred from a multi-tank (200) can flow into an injection line (SL) and be injected into a storage tank (100) through an injection nozzle.

[0113] The drawing illustrates, as an example, that the injection branch line (CL1) is connected to the second loading line (LL2). By providing the injection branch line (CL1) connecting the second loading line (LL2) and the injection line (SL), LNG stored in the multitank (200) can be injected and supplied to the storage tank (100) from the multitank (200) through the first filling line (FL1), the second loading line (LL2), the injection branch line (CL1), and the injection line (SL).

[0114] In addition, when a ship is performing a cool-down step for the purpose of lowering the temperature of the storage tank (100), such as when performing a ballast voyage with a small load after unloading LNG stored in a storage tank (100) at a demand location, or before loading LNG into the storage tank (100) at a supplier location or when performing maintenance on the storage tank (100), LNG for cool-down can be supplied to the storage tank (100) from the multi-tank (200) using the injection branch line (CL1).

[0115] A vessel according to the present embodiment may further include an engine (400) and a fuel supply unit for supplying fuel to the engine (400).

[0116] The engine (400) may be installed in the engine room (ER), and at least some of the devices constituting the fuel supply unit may be installed in the cargo compressor room (CR).

[0117] Here, the engine (400) may include a propulsion engine used for propulsion of the ship and a power generation engine used for generating power on board.

[0118] The fuel supply unit according to the present embodiment may include at least one of a fuel pump (310) that pressurizes and discharges LNG from a storage tank (100), a vaporizer (320) that vaporizes LNG pressurized by the fuel pump (310) and supplies it to an engine (400), and a compressor (330) that compresses boil-off gas (BOG) generated by natural vaporization of LNG stored in the storage tank (100) and supplies it to the engine (400).

[0119] The fuel supply unit further includes a liquefied gas line (VL) connecting a fuel pump (310), a vaporizer (320), and an engine (400), so that LNG stored in the storage tank (100) can flow through the liquefied gas line (VL) and be supplied as fuel to the engine (400) via the fuel pump (310) and the vaporizer (320).

[0120] The liquefied gas line (VL) may be equipped with one or more liquefied gas valves (VV), and by controlling each of the one or more liquefied gas valves (VV), the flow of fluid through the liquefied gas line (VL) may be controlled.

[0121] Although the drawing illustrates an example in which the fuel pump (310) is installed inside the storage tank (100), the fuel pump (310) may be installed outside the storage tank (100), or at least one may be installed inside and outside the storage tank (100) to pressurize LNG in stages. When the fuel pump (310) is installed outside the storage tank (100), the liquefied gas line (VL) may connect the storage tank (100), the fuel pump (310), the vaporizer (320), and the engine (400).

[0122] The fuel pump (310) of the present embodiment may be a means for pressurizing LNG so that the LNG is supplied at a pressure required by the engine (400).

[0123] Additionally, the compressor (330) may be a means for compressing the evaporation gas so that the evaporation gas is supplied at a pressure required by the engine (400).

[0124] The pressure of gaseous fuel required by the propulsion engine and the power generation engine may be different, and the pressure of gaseous fuel required by the propulsion engine may be higher than the pressure required by the power generation engine.

[0125] For example, the fuel pump (310) and compressor (330) may further include a means for pressurizing or compressing the fluid to the pressure required by the propulsion engine, and reducing the gaseous fuel to be supplied as fuel for the power generation engine from upstream of the power generation engine to the pressure required by the power generation engine.

[0126] Alternatively, it may be possible to have at least one fuel pump (310) and at least one compressor (330), and to have means for pressurizing or compressing fluid in at least one fuel pump (310) or compressor (330) to a pressure required by the power generation engine, and further pressurizing or compressing fluid to be supplied as fuel for the propulsion engine to a pressure required by the propulsion engine.

[0127] The fuel supply unit further includes a evaporative gas line (BL) connecting the storage tank (100), the compressor (330), and the engine (400), so that BOG from the storage tank (100) can flow through the evaporative gas line (BL) and be supplied as fuel to the engine (400) via the compressor (330).

[0128] The evaporation gas line (BL) can be connected to the storage tank (100) through a gas dome provided on the tank top of the storage tank (100).

[0129] The evaporation gas line (BL) may be equipped with one or more evaporation gas valves (BV), and by controlling each of the one or more evaporation gas valves (BV), the flow of evaporation gas through the evaporation gas line (BL) may be controlled.

[0130] Meanwhile, according to the present embodiment, LNG stored in the multi-tank (200) can also be supplied as fuel to the engine (400).

[0131] For example, LNG stored in a multi-tank (200) can be transferred to a storage tank (100) using the first charging line (FL1), and LNG can be supplied as fuel to an engine (400) from the storage tank (100) through a fuel supply unit.

[0132] In addition, LNG stored in the multi-tank (200) is supplied to the storage tank (100) using the injection branch line (CL1), and LNG is injected by the injection nozzle, so that LNG transferred from the multi-tank (200) to the storage tank (100) through the injection branch line (CL1) can exist in a gaseous state in the storage tank (100).

[0133] LNG transferred from the multi-tank (200) to the storage tank (100) through the injection branch line (CL1) may be supplied to the compressor (330) in a gaseous state and used as fuel for the engine (400).

[0134] According to this embodiment, LNG can be supplied as fuel to the engine (400) from the multi-tank (200) without having a separate fuel supply device for supplying fuel from the multi-tank (200) to the engine (400).

[0135] Although not shown in the drawing, by further providing a fuel branch line (not shown) connecting the multi-tank (200) to a vaporizer (320) or a liquefied gas line (VL), LNG can be supplied as fuel to the engine (400) from the multi-tank (200).

[0136] In case of providing additional fuel branch lines, the supply pump (210) should be adopted with specifications capable of pressurizing LNG to the pressure required by the engine (400).

[0137] However, even if the specifications of the supply pump (210) are insufficient to pressurize LNG to the pressure required by the engine (400), since the operating pressure of the multi-tank (200) is higher than the operating pressure of the storage tank (100) and the multi-tank (200) is positioned higher than the storage tank (100), LNG transferred from the multi-tank (200) to the storage tank (100) through the gravity and non-pressurized line (NL) may be supplied to the vaporizer (320) by the fuel pump (310) and used as fuel for the engine (400).

[0138] According to the present embodiment, an evaporation gas branch line (CL2) connecting the evaporation gas line (BL) and the multi-tank (200) may be further included.

[0139] By providing an evaporation gas branch line (CL2), evaporation gas can be supplied from the storage tank (100) to the multi-tank (200).

[0140] Additionally, the evaporation gas branch line (CL2) may be equipped with one or more evaporation gas branch valves (CV2), and by controlling the evaporation gas branch valves (CV2), the flow of evaporation gas through the evaporation gas branch line (CL2) may be controlled.

[0141] The evaporation gas branch line (CL2) can be connected to the multi-tank (200) from downstream of the compressor (330). That is, the evaporation gas compressed in the compressor (330) can be supplied to the multi-tank (200) through the evaporation gas branch line (CL2).

[0142] By supplying compressed evaporation gas to the multi-tank (200) using the evaporation gas branch line (CL2), the operating pressure of the multi-tank (200) can be controlled.

[0143] By utilizing the evaporation gas to maintain the pressure of the multi-tank (200), even if an excess of evaporation gas is generated in the storage tank (100), that is, an amount of evaporation gas exceeding the amount that can be processed by the engine (400), the evaporation gas can be utilized without being discarded.

[0144] In addition, when maintaining the multi-tank (200), the gas for gassing up the multi-tank (200) can be supplied to the multi-tank (200) using the evaporation gas branch line (CL2) at the stage of gassing up the multi-tank (200).

[0145] Meanwhile, according to the present embodiment, as a means for processing the evaporation gas generated in the storage tank (100), a re-liquefaction device (not shown) that re-liquefies the evaporation gas to generate re-liquefied evaporation gas (LNG) may be further included.

[0146] Any existing known re-liquefaction device may be adopted as the re-liquefaction device.

[0147] The re-liquefaction device may include a heat exchange means for cooling and re-liquefying the compressed evaporation gas in the compressor (330), or may be provided separately from the compressor (330) as a means for compressing the evaporation gas for re-liquefaction.

[0148] Typically, the re-liquefied vaporization gas re-liquefied in the re-liquefaction device is recovered into a storage tank (100). Since the operating pressure of the storage tank (100) is a low pressure of about 1 bara, a significant amount of the re-liquefied vaporization gas may be generated as flash gas during the process of recovering the re-liquefied vaporization gas into the storage tank (100), and thus, the amount of the re-liquefied vaporization gas actually recovered in a liquid state into the storage tank (100) is less than the amount of the vaporization gas re-liquefied in the re-liquefaction device.

[0149] According to the present embodiment, if a re-liquefaction device is further included, a re-liquefaction branch line (not shown) connected from the re-liquefaction device to the multi-tank (200) may be further included.

[0150] Since the operating pressure of the multi-tank (200) is higher than that of the storage tank (100), i.e., about 4 to 6 barg in this embodiment, when the re-liquefied vaporized gas is recovered to the multi-tank (200) through the re-liquefied branch line, the amount of flash gas generated is reduced compared to when the re-liquefied vaporized gas is recovered to the storage tank (100), and as a result, a larger amount of the re-liquefied vaporized gas can be recovered.

[0151]

[0152] According to one embodiment of the present invention described above, by providing a first charging line (FL1) to supply LNG stored in a multi-tank (200) to a storage tank (100), even LNG stored in the multi-tank (200) can be unloaded to a demander, thereby increasing the ship's operating distance and enabling more flexible ship operation.

[0153] In addition, by providing a spray branch line (CL1) to supply LNG stored in a multi-tank (200) to a storage tank (100), the pressure and temperature of the storage tank (100) can be kept low, and the cool-down stage of the storage tank (100) can be performed in advance before arriving at the supplier (terminal), thereby reducing the time spent at the supplier.

[0154] In addition, since LNG stored in the multi-tank (200) can be supplied to the fuel supply unit using at least one of the first charging line (FL1), the injection branch line (CL1), and the fuel branch line, the amount of LNG stored in the storage tank (100) that can be unloaded as cargo can be increased.

[0155] In addition, by providing an evaporation gas branch line (CL2), the evaporation gas generated in the storage tank (100) can be supplied to the multi-tank (200), thereby maintaining the pressure of the multi-tank (200) while usefully processing the evaporation gas.

[0156] In addition, by providing a re-liquefaction branch line and recovering the re-liquefaction vaporization gas generated in the re-liquefaction device to a multi-tank (200), the recovery rate of the re-liquefaction vaporization gas can be increased.

[0157] In addition, by providing a multi-tank (200), the quantity or capacity of the ballast tank can be reduced, so that a larger amount of LNG can be shipped.

[0158]

[0159] Hereinafter, a method for operating a ship according to one embodiment of the present invention described above will be described.

[0160] First, it may include a step of loading LNG into a storage tank (100) using at least one of the first loading line (LL1) and the second loading line (LL2) at an LNG supply source (terminal, etc.).

[0161] When loading LNG using only the second loading line (LL2), LNG from the supplier can be loaded into the storage tank (100) through the second loading line (LL2).

[0162] In addition, when loading LNG using the first loading line (LL1), LNG is loaded from the supplier to the multi-tank (200) through the first loading line (LL1), and the LNG stored in the multi-tank (200) can be transferred to the storage tank (100) through the first filling line (FL1).

[0163] At this time, some of the LNG transferred from the multi-tank (200) to the storage tank (100) through the first charging line (FL1) may be supplied to the storage tank (100) through the injection branch line (CL1) and the injection line (SL).

[0164] Meanwhile, before loading LNG into the storage tank (100), a cool-down step may be performed to lower the internal temperature of the storage tank (100) to a certain level or lower by supplying LNG stored in the multi-tank (200) to the storage tank (100) using at least one of the first charging line (FL1) and the injection branch line (CL1).

[0165] After loading LNG into the storage tank (100), the ship begins sailing to the place of demand. At this time, not only the storage tank (100) but also the multi-tank (200) must be filled with LNG.

[0166] In addition, according to the present embodiment, when a ship is sailing to a demand destination while loading LNG, a fuel supply step may be further included for sailing by generating propulsion and electric power by using LNG stored in at least one of a storage tank (100) and a multi-tank (200) as fuel for an engine (400).

[0167] In the fuel supply stage, LNG stored in the storage tank (100) is supplied to the fuel supply unit, and gas fuel in the amount of fuel required according to the load of the engine (400) can be supplied to the engine (400) from the fuel supply unit.

[0168] At this time, one or more of the steps of supplying LNG in a liquid state from the multi-tank (200) to the storage tank (100) through the first charging line (FL1), the step of supplying gas in a gaseous state from the multi-tank (200) through the injection branch line (CL1) and the injection line (SL), and the step of supplying LNG to the fuel supply unit through the fuel branch line from the multi-tank (200) may be performed.

[0169] In addition, the step of measuring the pressure of the multi-tank (200) while the ship is in operation may be included, and if the measured pressure of the multi-tank (200) becomes lower than a reference value, the step of supplying the evaporation gas from the storage tank (100) to the multi-tank (200) using the evaporation gas branch line (CL2) may be further included.

[0170] In the step of supplying the evaporation gas from the storage tank (100) to the multi-tank (200), the evaporation gas compressed in the fuel supply unit, particularly the compressor (330), can be supplied to the multi-tank (200).

[0171] When the amount of evaporation gas generated in the storage tank (100) during operation of the ship is greater than the amount of fuel required by the engine (400) and the amount required to maintain the pressure of the multi-tank (200), a step of re-liquefying the evaporation gas to generate re-liquefied evaporation gas can be performed.

[0172] The step of generating the re-liquefied evaporation gas may include a step of recovering the generated re-liquefied evaporation gas to at least one of the storage tank (100) and the multi-tank (200).

[0173] Additionally, in this embodiment, the vessel can load LNG from a supplier and then move to at least one demand source and unload LNG at one or more demand sources.

[0174] As an example, in this embodiment, a vessel can move from a supply source (A) to a first demand source (B) and a second demand source (C) to unload LNG.

[0175] Here, the operating distance from the supplier (A) to the first demand source (B) is longer than the distance from the first demand source (B) to the second demand source (C), and the operating distance from the supplier (A) to the first demand source (B) is called a long voyage, and the operating distance from the first demand source (B) to the second demand source (C) is called a short voyage.

[0176] In addition, the vessel may operate by including at least one of long-distance and short-distance operations, and the order and combination thereof may be applied in various ways with reference to this embodiment depending on conditions such as the amount of LNG that can be loaded, the location of each demand source, the amount of LNG unloading required by each demand source, the route, and the operating distance.

[0177] For example, a vessel according to the present embodiment may operate from a supply source (A) to a first demand source (B), may operate from a supply source (A) to a second demand source (C), and may operate from a supply source (A) to a third demand source (D), which is another demand source, in order to unload LNG at each destination (demand source).

[0178] Additionally, the vessel according to the present embodiment may be able to operate from the first destination, the first demand source (B), to another destination, the second demand source (C), and may also be able to operate from the second destination, the second demand source (C), to another destination, the third demand source (D).

[0179] In comparison, existing ships equipped only with a storage tank (100) and not with a multi-tank (200) could only operate either long-distance or short-distance, for example, from a supply source (A) to a first demand source (B) or from a supply source (A) to a second demand source (C).

[0180] According to this embodiment, after loading LNG from a supplier (A) into both a storage tank (100) and a multi-tank (200), the LNG is moved to a first demand source (B) located at a long distance, and the LNG loaded in the storage tank (100) is unloaded to a maximum, for example, 100% or less, and the LNG stored in the multi-tank (200) is used as fuel to move from the first demand source (B) to a second demand source (C) located at a short distance, and the remaining LNG is unloaded as cargo.

[0181] Alternatively, the second demand source (C) may not only be a demand source that receives LNG, but may also be a supply source that can load LNG onto a vessel, in which case LNG may be loaded onto a vessel at the second demand source (C) and then moved for the purpose of unloading LNG at another demand source.

[0182] In addition, according to the present embodiment, before arriving at a supplier that supplies LNG to load LNG onto a ship or a port for performing maintenance on the ship, the cool-down of the storage tank (100) can be performed using the LNG remaining in the multi-tank (200) or the gassing-up of the multi-tank (200) can be performed using the evaporation gas remaining in the storage tank (100), so that the time spent anchored at the supplier can be shortened.

[0183]

[0184] As described above, embodiments of the present invention have been described. It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms, in addition to the embodiments described above, without departing from the spirit or scope thereof. Therefore, the above-described embodiments should be considered illustrative rather than restrictive, and accordingly, the present invention is not limited to the above description, but may be modified within the scope of the appended claims and their equivalents.

[0185] <Explanation of symbols>

[0186] 100: Storage tank

[0187] 200: Multitank 210: Supply pump

[0188] 310: Fuel pump 320: Carburetor

[0189] 330: Compressor 400: Engine

[0190] LL1: 1st loading line LV1: 1st loading valve

[0191] LL2: Second loading line LV2: Second loading valve

[0192] FL1: 1st charging line FV1: 1st charging valve

[0193] FL2: Second charging line FV2: Second charging valve

[0194] NL: Non-pressurized line NV: Non-pressurized valve

[0195] SL: Injection line SV: Injection valve

[0196] CL1: Injection branch line CV1: Injection branch valve

[0197] VL: Liquefied gas line VV: Liquefied gas valve

[0198] BL: Evaporative gas line BV: Evaporative gas valve

[0199] CL2: Evaporation gas branch line CV2: Evaporation gas branch valve

Claims

1. One or more storage tanks installed under the deck and storing LNG; and A vessel including a liquefied gas storage tank, comprising one or more multi-tanks installed on the upper deck of the vessel and storing LNG for multiple purposes.

2. In claim 1, The LNG stored in the above multi-tank is A vessel containing a liquefied gas storage tank used for one or more of the following purposes: cargo, fuel, maintenance of the storage tank, or maintenance of the pressure or temperature of the storage tank.

3. In claim 1, A vessel including a liquefied gas storage tank, wherein the operating pressure of the above multi-tank is higher than the operating pressure of the above storage tank.

4. In claim 1, The above multi-tank is, A vessel including a liquefied gas storage tank, which is placed on the stern side or adjacent to the engine room on the bow side.

5. In claim 1, Includes a loading manifold for connecting an LNG supplier and a vessel to receive LNG; A first loading line connected from the loading manifold to the multitank; and A vessel including a liquefied gas storage tank, further comprising at least one of a second loading line connected from a loading manifold to the storage tank.

6. In claim 1, A vessel including a liquefied gas storage tank, further comprising a first charging line connecting the multi-tank and the storage tank and supplying LNG from the multi-tank to the storage tank.

7. In claim 6, engine; and Further comprising a fuel supply unit for supplying LNG as fuel to the engine from the above storage tank; A ship including a liquefied gas storage tank, wherein LNG transferred to a storage tank through the first charging line is supplied to an engine through a fuel supply unit from the storage tank.

8. In claim 1, An injection nozzle provided in the upper space of the storage tank and supplying LNG to cool the upper space; An injection line for transporting LNG to be injected through the above injection nozzle; and A vessel including a liquefied gas storage tank, further comprising an injection branch line connecting the multi-tank and the injection line, and for injecting LNG from the multi-tank to the storage tank through the injection line.

9. In claim 8, engine; and Further comprising a fuel supply unit for supplying LNG as fuel to the engine from the above storage tank; A ship including a liquefied gas storage tank, wherein LNG transferred from a multi-tank to a storage tank through the above-mentioned injection branch line is supplied to an engine through a fuel supply unit from the storage tank.

10. In claim 1, A compressor that compresses gas in a gaseous state discharged from the above storage tank; and A vessel including a liquefied gas storage tank, further comprising an evaporation gas branch line connecting the compressor and the multitank and supplying gas compressed by the compressor to the multitank.

11. In claim 1, A re-liquefaction device that re-liquefies the evaporation gas generated by natural evaporation of LNG stored in the above storage tank to generate re-liquefied evaporation gas; and A vessel including a liquefied gas storage tank, further comprising a re-liquefaction branch line for recovering re-liquefied vaporized gas generated in the re-liquefaction device to the multi-tank.

12. A method of operating a ship including one or more storage tanks installed under the deck and storing LNG; and one or more multi-tanks installed on the deck of the ship and storing LNG for multiple purposes; A method for operating a vessel including a liquefied gas storage tank, comprising the step of loading LNG from an LNG supply source into at least one of the storage tanks and multi-tanks.

13. In claim 12, A method for operating a ship including a liquefied gas storage tank, further comprising a step of transferring LNG loaded in the multi-tank to the storage tank in a liquid state.

14. In claim 12, A method for operating a ship including a liquefied gas storage tank, further comprising a step of supplying LNG loaded in the multi-tank by spraying it into the storage tank, thereby lowering the temperature of the storage tank.

15. In claim 14, The LNG supplied by injection from the above multi-tank to the above storage tank is in a gaseous state, A method for operating a ship including a liquefied gas storage tank, further comprising a step of supplying the gas as fuel for the ship.

16. In claim 13, A step of supplying LNG supplied from the above multi-tank to the storage tank to the fuel supply unit; and A method for operating a ship including a liquefied gas storage tank, further comprising a step of vaporizing LNG supplied to the fuel supply unit and supplying it as fuel for an engine.

17. In claim 12, A step of measuring the pressure of the above multi-tank; and A method for operating a ship including a liquefied gas storage tank, further comprising: a step of supplying evaporation gas generated by natural vaporization of LNG stored in the storage tank to the multi-tank to increase the pressure of the multi-tank when the measured pressure of the multi-tank becomes lower than a reference value; 18. In claim 12, A step of maintaining the operating pressure of the above multi-tank higher than the operating pressure of the above storage tank; A step of re-liquefying the evaporation gas generated by natural vaporization of LNG stored in the above storage tank to generate re-liquefied evaporation gas; and A method for operating a ship including a liquefied gas storage tank, further comprising a step of recovering the re-liquefied evaporated gas to the multi-tank.

19. In claim 12, A step of unloading LNG stored in the above storage tank to the first demand source; and A method for operating a ship including a liquefied gas storage tank, further comprising: a step of moving LNG stored in the multi-tank as fuel to a second demand source.

20. In claim 12, A method for operating a ship including a liquefied gas storage tank, further comprising a step of supplying LNG stored in the multi-tank to the storage tank to cool down the storage tank before the ship arrives at the destination.

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