CN114929572A

CN114929572A - Liquefied gas supply system and method for ship and liquefied gas fuel supply system for ship

Info

Publication number: CN114929572A
Application number: CN202080086411.0A
Authority: CN
Inventors: 崔眞溶
Original assignee: Daewoo Shipbuilding and Marine Engineering Co Ltd
Current assignee: Hanwha Ocean Co Ltd
Priority date: 2019-12-24
Filing date: 2020-12-09
Publication date: 2022-08-19
Also published as: WO2021132955A1; JP2023508857A; JP7445763B2

Abstract

The present invention relates to a liquefied gas supply system and method. The liquefied gas supply system and method can treat the boil-off gas generated when liquefied gas is supplied to the storage tank of the ship in the ship without returning the boil-off gas to the outside. Further, the invention relates to a liquefied gas fuel supply system for a ship. The liquefied gas fuel supply system for a ship can treat the boil-off gas generated when liquefied gas fuel is supplied to a fuel tank of the ship without returning the boil-off gas to the outside. A liquefied gas supply system according to the present invention is a system for supplying liquefied gas from a liquefied gas supply vessel to a vessel including a plurality of liquefied gas storage tanks, the system including: a liquefied gas line for supplying liquefied gas from the liquefied gas supply vessel to any one of the plurality of liquefied gas storage tanks; a gas discharge line for discharging a boil-off gas generated when the liquefied gas is supplied to any one of the liquefied gas storage tanks; and a gas supply line for supplying the boil-off gas to one or more other liquefied gas storage tanks.

Description

Liquefied gas supply system and method for ship and liquefied gas fuel supply system for ship

Technical Field

The present invention relates to a liquefied gas supply system and method that can treat boil-off gas generated when liquefied gas is supplied to a tank of a ship in the ship without returning the boil-off gas to the outside.

The present invention also relates to a liquefied gas fuel supply system for a ship, which can treat a boil-off gas generated when liquefied gas fuel is supplied to a ship fuel tank in the ship without returning the boil-off gas to the outside.

Background

Generally, natural gas is produced in a Liquefied Natural Gas (LNG) state at a production site and then transported to a natural gas receiving station on land by an LNG carrier.

An empty LNG storage tank provided on a ship is generally filled with an inert gas to prevent gas explosion. That is, a replacement process of replacing the inert gas filled in the storage tank with natural gas is performed in a commissioning stage before the LNG carrier is operated or before LNG is stored in the LNG storage tank of the LNG carrier.

In addition, after the replacement process, a cooling process is performed to reduce the temperature inside the tank, and then LNG may be supplied into the tank.

Meanwhile, when the cooling process is performed and LNG is supplied, a large amount of boil-off gas is generated, which is generally returned to the gas receiving station to maintain the pressure in the tank.

For example, about 4 to 7MT/hr of boil-off gas is generated in the cooling process stage, and about 7 to 9MT/hr of boil-off gas is generated in the LNG supply stage. When supplying LNG, as described above, about 4 to 9MT/hr of boil-off gas is returned from the ship to the gas receiving station at each stage, and the returned boil-off gas is recovered by reliquefaction or is treated by burning in a GCU (gas combustion unit).

Disclosure of Invention

Technical problem to be solved

In addition, as a countermeasure for solving the problem of environmental pollution, the operation of an LNG refueling ship is also activated as the LNG refueling ship is expanded and popularized. The LNG tanker is a ship that travels to a place where an LNG ship is operated and supplies LNG from the LNG tanker to the LNG tanker at sea.

Similarly, when LNG is supplied from an LNG refueling ship to an LNG fuelling ship, a large amount of boil-off gas is also generated in the LNG fuelling ship that receives the LNG.

Since the LNG-fueled ship is loaded with cargo, it is not easy to install a pipe to recover the boil-off gas, and the boil-off gas is a combustible substance, thereby posing a risk of fire or explosion. Preferably, boil-off gas generated when LNG is supplied is recovered from the LNG-fueled ship and then processed at the LNG refueling ship.

The empty LNG fuel tank is typically filled with an inert gas prior to receiving the LNG fuel to prevent gas explosion. That is, a replacement process of replacing inert gas filled in a tank with natural gas is required at a test run stage before the start of the operation of the LNG-fueled ship or before the LNG fuel is stored in an empty LNG fuel tank.

In addition, after the substitution process, a cooling process of reducing the internal temperature of the fuel tank is performed, and then LNG may be supplied to the fuel tank.

On the other hand, when performing the cooling process and supplying LNG, a large amount of boil-off gas is generated, which is usually returned to the gas receiving station to maintain the pressure in the tank.

A technique of supplying LNG to an LNG tanker at sea using not only these LNG tankers but also various LNG ships having LNG tanks such as LNG fuel tanks (for example, a technique of supplying LNG for test runs to an LNG carrier) using the LNG tanker has been actively discussed.

As described above, in order to supply LNG to the empty LNG storage tanks of the LNG carrier to be commissioned, the replacement process and the cooling process need to be performed first. That is, in order to supply LNG for a test run to the LNG carrier by the LNG tanker, it is necessary to directly treat the boil-off gas of about 4 to 9MT/hr recovered from the LNG carrier at each stage in the LNG tanker.

However, the GCU capacity of lng tankers is limited. In fact, in the case of an LNG refueling ship having an LNG refueling function, which is being constructed in korea, and an LNG refueling ship actually constructed by a korean shipyard and operated at a european port, the GCU capacity is less than 1 ton.

In addition, since the LNG carrier in the commissioning phase does not yet have an operation state of the GCU or the reliquefaction apparatus capable of handling the boil-off gas, it can be said that the boil-off gas cannot be handled by the LNG carrier itself.

As described above, practically, all of the boil-off gas generated during cooling and supply cannot be handled without discharging the boil-off gas into the atmosphere.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a system and a method for supplying liquefied gas to a ship, which are capable of automatically processing the liquefied gas on an LNG carrier without recovering the vaporized gas generated when LNG is supplied to an LNG storage tank of the LNG carrier or LNG for test operation, on the LNG carrier.

Further, the present invention provides a liquefied gas fuel supply system for a ship, which can automatically handle boil-off gas generated when LNG is supplied to an LNG fuel tank of an LNG tanker without recovering the boil-off gas to an LNG tanker.

Means for solving the problems

To achieve the above object, according to one aspect of the present invention, there is provided a liquefied gas supply system that supplies liquefied gas from a liquefied gas supply vessel to a vessel including a plurality of liquefied gas storage tanks, comprising: a liquefied gas line for supplying liquefied gas to any one of the plurality of liquefied gas storage tanks; a gas discharge line for discharging a boil-off gas generated by supplying a liquefied gas to any one of the liquefied gas storage tanks; a gas supply line for supplying the boil-off gas to one or more other liquefied gas storage tanks.

Preferably, a heater may be further included for heating the boil-off gas discharged along the gas discharge line, and the boil-off gas heated at the heater may be supplied to one or more other liquefied gas storage tanks through the gas supply line.

Preferably, the boil-off gas generated when the liquefied gas is supplied to any one of the liquefied gas storage tanks may be supplied to the other liquefied gas storage tank.

Preferably, the boil-off gas generated when the liquefied gas is supplied to any one of the liquefied gas storage tanks may be supplied to all of the remaining other liquefied gas storage tanks.

Preferably, the liquefied gas line connects the liquefied gas supply vessel and the liquefied gas storage tank, and may include: a liquid cross-line for conveying liquefied gas from the liquefied gas supply vessel; a liquid line for branching and supplying the received liquefied gas to each liquefied gas storage tank through the liquid cross-line.

Preferably, the liquid line may further comprise one or more isolation valves for separating the liquid line so that liquefied gas is not supplied to one or more other liquefied gas storage tanks when liquefied gas is supplied through the liquid cross-line.

Preferably, the isolation valve may be installed between the point at which the liquid cross line and the liquid line intersect and the point at which the isolation valve branches off to the first intersected liquefied gas storage tank.

In order to achieve the above object, according to another aspect of the present invention, there is provided a method of supplying liquefied gas from a liquefied gas supply vessel to a vessel including a plurality of liquefied gas storage tanks, the liquefied gas supply method including the steps of: a liquefied gas supply step of supplying liquefied gas from a liquefied gas supply vessel to any one of the plurality of liquefied gas storage tanks; a boil-off gas discharging step of discharging a boil-off gas generated by supplying the liquefied gas to any one of the liquefied gas storage tanks; a replacement gas supply step of supplying the boil-off gas discharged from any one of the liquefied gas storage tanks to one or more other liquefied gas storage tanks of the plurality of liquefied gas storage tanks.

Preferably, the boil-off gas discharged in the boil-off gas discharge step may be heated, and the heated boil-off gas may be supplied to one or more other liquefied gas storage tanks.

Preferably, the boil-off gas generated when the liquefied gas is supplied to any one of the liquefied gas storage tanks may be supplied to all of the remaining liquefied gas storage tanks.

Preferably, when liquefied gas is supplied to any one of the liquefied gas storage tanks, it may be shut off so that liquefied gas is not supplied to one or more other liquefied gas storage tanks.

According to another aspect of the present invention for achieving the above object, there is provided a supply method of supplying liquefied gas for a test run of a vessel from a liquefied gas supply vessel to a liquefied gas carrier vessel including a plurality of liquefied gas storage tanks, the liquefied gas supply method for a test run of a vessel including the steps of: a step of supplying liquefied gas for cooling, from the liquefied gas supply vessel, to a tank to be cooled of the plurality of liquefied gas storage tanks, which is to be subjected to a cooling process, by using a gas stripping line for injection into the liquefied gas storage tanks; a step of discharging cooled boil-off gas, in which boil-off gas generated in the storage tank to be cooled when liquefied gas is supplied to the storage tank to be cooled is discharged through a gas line provided for discharging from the liquefied gas storage tank; and a step of supplying a first replacement gas for supplying the boil-off gas discharged from the storage tank to be cooled to a first replacement storage tank of the plurality of liquefied gas storage tanks to which a replacement process is to be performed.

Preferably, a step of discharging a first inert gas, which is filled with an inert gas, may be further included, the inert gas discharged from the first replacement storage tank by supplying the boil-off gas to the first replacement storage tank being supplied to the gas exhaust tower through a liquid line provided for storing or discharging the liquefied gas in or from the liquefied gas storage tank and a second connection line connecting the liquid line and the gas exhaust tower.

Preferably, the step of supplying the first replacement gas may further include a boil-off gas treatment step of compressing and heating the boil-off gas discharged from the storage tank to be cooled before being supplied to the first replacement storage tank.

Preferably, the amount of boil-off gas discharged from the storage tank to be cooled is equal to or greater than the amount of boil-off gas required for the replacement process of the first storage tank to be replaced, and the replacement process of the first storage tank to be replaced may be completed when cooling of the storage tank to be cooled is completed.

Preferably, the following steps may be included: a liquefied gas supply step of preparing the tank to be cooled to store liquefied gas when cooling of the tank to be cooled is completed, and supplying the liquefied gas to the tank to be supplied in preparation for storing the liquefied gas, using a liquid line provided for storing the liquefied gas in the liquefied gas storage tank or discharging the liquefied gas from the liquefied gas storage tank; a boil-off gas discharge step of discharging a boil-off gas generated in the storage tank to be supplied while supplying the liquefied gas to the storage tank to be supplied, through the gas line; and a step of supplying a second replacement gas, in which the boil-off gas discharged in the boil-off gas discharge step is supplied to a second tank to be replaced in the plurality of liquefied gas storage tanks ready for a replacement process.

Preferably, a step of discharging a second evaporation gas, the second storage tank to be replaced being filled with an inert gas, the evaporation gas being supplied to the second storage tank to be replaced and the inert gas being discharged from the second storage tank to be replaced, the inert gas being supplied to the gas discharge tower by a second connection line connecting the liquid line and the gas discharge tower.

Preferably, the liquid line and the storage tank to be supplied are connected by a first liquid line, the liquid line and the second storage tank to be replaced are connected by a third liquid line, and an isolation valve may be provided between a point at which the first liquid line branches from the liquid line and a point at which the third liquid line branches, the isolation valve being closed in the step of discharging the second replacement gas.

Preferably, the step of supplying the second replacement gas may further include a second boil-off gas treatment step of compressing and heating the boil-off gas discharged from the storage tank to be supplied before supplying the boil-off gas to the second storage tank to be replaced.

In order to achieve the above object, according to another aspect of the present invention, there is provided a liquefied gas supply system for a test run of a ship for supplying liquefied gas for a test run from a liquefied gas supply ship to a liquefied gas carrier ship including a plurality of liquefied gas storage tanks, the liquefied gas supply system for a test run of a ship including: a gas stripping line configured to inject the liquefied gas from the liquefied gas supply vessel to the liquefied gas storage tanks and to deliver the liquefied gas for cooling to storage tanks to be cooled, in which a cooling process is to be performed among the plurality of liquefied gas storage tanks; a liquid line provided to store the liquefied gas into the liquefied gas storage tank or discharge the liquefied gas from the liquefied gas storage tank, for supplying the liquefied gas for test run to the storage tank to be supplied in which the liquefied gas is ready to be stored after completion of cooling; and a gas line provided to discharge gas from the liquefied gas storage tank for discharging evaporation gas generated in the storage tank to be cooled or storage tank to be supplied when liquefied gas is supplied to the storage tank to be cooled or storage tank to be supplied. Wherein the vapor gas discharged from the storage tank to be cooled and the storage tank to be supplied is delivered to the storage tank to be replaced in the plurality of liquefied gas storage tanks to be subjected to the replacement process through the gas stripping line.

Preferably, a second connection line connecting the liquid line and the gas exhaust tower may be further included, the storage tank to be replaced is filled with an inert gas, and the inert gas discharged from the storage tank to be replaced when the evaporation gas is supplied to the storage tank to be replaced may be delivered to the gas exhaust tower through the liquid line and the second connection line.

Preferably, the method comprises the following steps: a supply-use liquid branch line for connecting the liquid line with the storage tank to be cooled or the storage tank to be supplied; and a liquid branch line for replacement for connecting the liquid line and the tank to be replaced. The storage tank to be cooled or the storage tank to be supplied may further include an isolation valve that is provided between a point at which the liquid branch line branches from the liquid line and a point at which the replacement liquid branch line branches, and that isolates a path of the liquid line through which the liquefied gas that is sent to the storage tank to be cooled or the storage tank to be supplied flows and a path of the liquid line through which the inert gas that is discharged from the storage tank to be replaced flows from each other by open-close control.

In order to achieve the above object, according to an aspect of the present invention, there is provided a liquefied gas supply system that supplies liquefied gas from a liquefied gas supply vessel to a vessel including a plurality of liquefied gas storage tanks, the liquefied gas supply system including: a liquefied gas line for supplying liquefied gas from the liquefied gas supply vessel to any one of the plurality of liquefied gas storage tanks; a gas supply line for discharging boil-off gas generated when liquefied gas is supplied to any one of the liquefied gas storage tanks, and supplying to the one or more other liquefied gas storage tanks. Further comprising an isolation valve for discharging gas discharged from the liquefied gas storage tank receiving the boil-off gas by means of the liquefied gas line, wherein the isolation valve is provided in the liquefied gas line between the liquefied gas storage tank receiving the liquefied gas through the liquefied gas line and the liquefied gas storage tank receiving the boil-off gas, and shuts off the flow of the liquefied gas and the boil-off gas flowing along the liquefied gas line without mixing them.

Preferably, further comprising, a manifold; and a cross line for connecting the manifold and the liquefied gas line, wherein the isolation valve may be a three-way valve provided at a point where the cross line and the liquefied gas line intersect.

Preferably, a heater for heating boil-off gas discharged along the gas discharge line is further included, and boil-off gas heated by the heater may be supplied to one or more other liquefied gas storage tanks through the gas supply line.

Preferably, the gas discharged from the liquefied gas storage tank receiving the boil-off gas is an inert gas, further comprising a connecting line for connecting the liquefied gas line and a gas discharge tower, wherein the inert gas can be transferred from the liquefied gas storage tank to the gas discharge tower.

In order to achieve the above object, according to another aspect of the present invention, there is provided a liquefied gas supply method of supplying liquefied gas from a liquefied gas supply vessel to a vessel including a plurality of liquefied gas storage tanks, the liquefied gas supply method including the steps of: a liquefied gas supply step of supplying liquefied gas from a liquefied gas supply vessel to any one of the plurality of liquefied gas storage tanks; a boil-off gas discharge step of discharging boil-off gas generated when liquefied gas is supplied to any one of the liquefied gas storage tanks; a replacement gas supply step of supplying the boil-off gas discharged from any one of the liquefied gas storage tanks to one or more other liquefied gas storage tanks among the plurality of liquefied gas storage tanks; and an inert gas discharge step of discharging the inert gas filled in the liquefied gas storage tank receiving the boil-off gas due to the receipt of the boil-off gas, wherein the inert gas is discharged through a line supplying the liquefied gas to the liquefied gas storage tank.

Preferably, the inert gas discharging step may further include an isolating step of isolating a portion, through which the liquefied gas flows into the liquefied gas storage tank and a portion, through which the inert gas flows, from each other in a line for supplying the liquefied gas into the liquefied gas storage tank.

In order to achieve the above object, according to another aspect of the present invention, there is provided a liquefied gas supply system for a trial operation of a vessel for supplying liquefied gas for a trial operation from a liquefied gas supply vessel to a liquefied gas carrier vessel including a plurality of liquefied gas storage tanks, in which each of the plurality of liquefied gas storage tanks is provided with: a liquid branch line for conveying liquefied gas; a gas stripping branch line for injecting liquefied gas; and a gas branch line for delivering the boil-off gas. And comprises the following steps: a gas line connecting each of the gas branch lines; and a liquid line connecting each of the liquid branch lines. The plurality of liquefied gas storage tanks are filled with an inert gas, and include: a tank to be replaced to which a replacement process is to be performed; and preparing a storage tank to receive liquefied gas after the replacement process is completed. Further comprising an isolation valve for controlling a path through which the boil-off gas discharged from the storage tank to be filled with the liquefied gas is sent to the storage tank to be replaced while supplying the liquefied gas using a liquid branch line or a gas stripping line connected to the storage tank to be filled with the liquefied gas, and through which the inert gas filled in the storage tank to be replaced is discharged.

Preferably, a liquid cross-line is further included, the liquid cross-line connecting the liquid line and a manifold of the liquefied gas carrier vessel, and the isolation valve may be a three-way valve provided at a point where the liquid line and the liquid cross-line are connected.

Preferably, the isolation valve may be provided between a point at which a liquid branch line of the storage tank ready to receive liquefied gas is connected to the liquid line and a point at which a liquid branch line of the storage tank to be replaced is connected to the liquid line.

Preferably, the gas line is provided with: a compressor for compressing the boil-off gas; and heating the boil-off gas compressed by the compressor, so that the boil-off gas transferred from the storage tank to be supplied with liquefied gas to the replacement storage tank can be compressed and heated.

Preferably, the storage tank prepared to receive liquefied gas comprises: a storage tank to be cooled that is an object of the replacement process to be subjected to a cooling process; and a storage tank to be supplied, which is an object of the cooling process to which a liquefied gas supply process for a commissioning is to be performed, such that the storage tank to be cooled may receive the liquefied gas through the gas stripping branch line, and the storage tank to be supplied may receive the liquefied gas through the liquid branch line.

Preferably, the storage tank to be replaced includes: a first displacement storage tank that receives boil-off gas from the storage tank to be cooled; and a second replacement storage tank that receives boil-off gas from the storage tank to be supplied.

In order to achieve the above object, according to an aspect of the present invention, there is provided a system for supplying liquefied gas fuel from a liquefied gas supply vessel to a liquefied gas fuel vessel including two or more liquefied gas fuel tanks, the liquefied gas fuel supply system of the vessel including: a first fuel tank for storing liquefied gaseous fuel; and a second fuel tank for storing liquefied gas fuel, so that liquefied gas fuel is supplied from the liquefied gas supply vessel using a liquid branch pipe or a gas stripping branch pipe connected to the first fuel tank, and vapor gas discharged from the first fuel tank is supplied as replacement gas to the second fuel tank through a gas line.

Preferably, in the gas line there are provided: a compressor for compressing the boil-off gas; and a heater for heating the evaporation gas compressed by the compressor, so that the evaporation gas delivered from the first fuel tank to the second fuel tank can be compressed, heated and supplied.

Preferably, it may further include: a liquid line for connecting each of the liquid branch lines; an isolation valve provided between a point at which the liquid branch line of the first fuel tank branches from the liquid line and a point at which the liquid branch line of the second fuel tank branches from the liquid line.

Preferably, when liquefied gas is supplied to the first fuel tank using the liquid branch line, gas discharged from the second fuel tank is discharged through the liquid branch line connected to the second fuel tank, and the isolation valve may be closed.

Preferably, a first connection line for connecting the liquid branch line of the second fuel tank and the rear end of the isolation valve may be further included.

Preferably, when the liquefied gas is supplied to the first fuel tank through the liquid branch line, the gas discharged from the second fuel tank may be discharged to the gas discharge tower through the liquid line and the first connection line.

Effects of the invention

According to the marine liquefied gas supply system and method and the marine liquefied gas fuel supply system of the present invention, when LNG is supplied to an LNG storage tank (e.g., an LNG fuel tank of an LNG carrier or an LNG fuel ship, etc.), boil-off gas generated in the LNG storage tank can be self-treated in the LNG carrier without being recovered to an LNG supply site.

In particular, when LNG is to be supplied during a commissioning phase of the LNG carrier or the LNG tanker or in a state where the LNG storage tank is empty, boil-off gas generated when the LNG chilling process and the LNG supply process are performed does not have to be recovered in the LNG tanker but is handled by the LNG carrier or the LNG tanker itself.

Therefore, LNG for commissioning can be supplied to an LNG carrier or an LNG fuelled ship by an LNG refueling ship at sea.

In addition, it is not necessary to force the vaporization of LNG in the displacement process.

In addition, the boil-off gas treatment and the LNG supply may be simultaneously performed on the ship to which the LNG is supplied.

Drawings

Fig. 1 is a conceptual diagram schematically illustrating a liquefied gas supply system according to an embodiment of the present invention.

Fig. 2 is a view illustrating a fluid flow state when cooling a fourth storage tank of a liquefied gas supply system according to an embodiment of the present invention.

Fig. 3 is a view showing a fluid flow state when cooling a fourth storage tank of a liquefied gas supply system according to another embodiment of the present invention.

Fig. 4 is a view illustrating a fluid flow state when LNG is supplied to a fourth storage tank of the liquefied gas supply system according to an embodiment of the present invention.

Fig. 5 is a view illustrating a fluid flow state when LNG is supplied to a fourth storage tank of a liquefied gas supply system according to another embodiment of the present invention.

Fig. 6 is a conceptual diagram schematically illustrating a liquefied gas fuel supply system for a ship according to an embodiment of the present invention.

Fig. 7 is a view showing a fluid flow state when cooling a first fuel tank of a liquefied gas fuel supply system for a ship according to an embodiment of the present invention.

Fig. 8 is a view showing a fluid flow state when cooling a first fuel tank of a marine liquefied gas fuel supply system according to another embodiment of the present invention.

Fig. 9 is a view showing a fluid flow state when LNG is supplied to a first fuel tank of a marine liquefied gas fuel supply system according to an embodiment of the present invention.

Fig. 10 is a view showing a flow state of fluid when LNG is supplied to a first fuel tank of a marine liquefied gas fuel supply system according to another embodiment of the present invention.

Detailed Description

For a fuller understanding of the operational advantages of the present invention and the objects attained by its practice, reference should be made to the accompanying drawings which illustrate a preferred embodiment of the invention and to the contents of which are illustrated in the accompanying drawings.

The constitution and action of the preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Here, when reference numerals are given to components in each drawing, it should be noted that the same components are denoted by the same reference numerals as much as possible even though they are denoted by different drawings. In addition, the following embodiments may be changed into various forms, and the scope of the present invention is not limited to the following embodiments.

In the embodiments of the present invention described later, the liquefied gas may be a liquefied gas that is liquefied at low temperature and is transportable, for example, LNG (liquefied natural gas), LEG (liquefied ethane), LPG (liquefied petroleum gas), liquefied ethylene, liquefied propylene, or the like; or may be a liquid gas such as liquefied carbon dioxide, liquefied hydrogen, or liquefied ammonia, or the like. However, in the examples described below, LNG, which is a typical liquefied gas, is applied as an example.

In the embodiments described below, a liquefied natural gas Carrier (LNG Carrier) that transports LNG as a cargo is described as an example, but the present invention can be applied to all offshore structures or ships such as an LNG fuel Carrier that includes a liquefied gas storage tank such as an LNG FSRU (floating storage and regasification unit) that includes a storage tank for storing LNG, an LNG FPSO (floating production and storage offloading unit), and an LNG RV (reliquefaction ship), or an LNG fuel Carrier that includes an engine that uses liquefied gas as fuel.

In the embodiments described below, the storage tank is a concept including all cargo tanks, fuel tanks, and the like, regardless of the name, as long as the tank stores liquefied gas.

Hereinafter, a marine liquefied gas supply system and method and a marine liquefied gas fuel supply system according to embodiments of the present invention will be described with reference to fig. 1 to 10.

A ship according to an embodiment of the present invention includes: a plurality of LNG storage tanks (T1, T2, T3, T4); a manifold for connecting a ship or a receiving station that supplies LNG, such as an LNG filling station that supplies LNG to a plurality of LNG storage tanks (T1, T2, T3, and T4); and a fluid transfer line for connecting the manifold to a plurality of LNG storage tanks (T1, T2, T3, T4).

The fluid delivery tube includes: a liquefied gas line that supplies liquefied gas from the LNG supply vessel to one of the plurality of LNG storage tanks; a gas discharge line that discharges boil-off gas generated by supplying LNG to any one of the LNG storage tanks; and a gas supply line supplying boil-off gas to one or more other LNG storage tanks.

In the present embodiment described later, the liquefied gas line may refer to a Liquid Line (LL), liquid branch lines (LL1, LL2, LL3, LL4), a gas Stripping Line (SL), and gas stripping branch lines (SL1, SL2, SL3, SL 4).

In addition, the gas discharge line may refer to a Gas Line (GL), gas branch lines (GL1, GL2, GL3, GL4), and first connecting line (CL1) and second connecting line (CL2), or when gas flows along Liquid Line (LL) and liquid branch lines (LL1, LL2, LL3, and LL4), the gas discharge line may refer to Liquid Line (LL) and liquid branch lines (LL1, LL2, LL3, and LL 4).

In addition, the gas supply line may refer to a Gas Line (GL) and gas branch lines (GL1, GL2, GL3, and GL 4).

In the present embodiment, an example is described in which a ship is connected to an LNG refueling ship, and LNG is supplied from the LNG refueling ship to LNG storage tanks (T1, T2, T3, and T4) through a manifold.

In addition, in the embodiment of the present invention, an example will be given in which LNG is supplied from an LNG refueling ship for the purpose of commissioning of the ship for initial cooling and commissioning of an LNG storage tank. However, the present invention is not limited thereto, and an LNG ship equipped with two or more LNG tanks, in the case where the LNG tanks thereof are supplied with LNG, for example, an LNG fuel tank or an LNG storage tank of the LNG ship, etc., may be variously applied in any case.

In addition, although not shown in the drawings, the ship according to the present embodiment may include: a main engine generating propulsion energy with LNG stored in LNG storage tanks (T1, T2, T3, T4) as fuel; a power generation engine generating electric power using LNG stored in the LNG storage tanks (T1, T2, T3, T4) as fuel; a fuel supply unit for supplying LNG stored in the LNG storage tanks (T1, T2, T3, T4) or boil-off gas generated by natural vaporization of the LNG to the main engine and the power generation engine to be used as fuel; a reliquefaction unit for reliquefying the boil-off gas and recovering the reliquefied boil-off gas to LNG storage tanks (T1, T2, T3, T4); and a gas treatment unit (100, 200) for treating the boil-off gas or the gas discharged from the engine.

In addition, a plurality of LNG storage tanks (T1, T2, T3, T4) may be installed, and in the present embodiment, as shown in fig. 1 to 5, a ship having four LNG storage tanks (T1, T2, T3, T4) is shown as an example. As described above, in the present embodiment, the example of four LNG storage tanks (T1, T2, T3, and T4) is described, but the present invention is not limited thereto. In addition, in the present embodiment, the LNG storage tanks mounted bow to stern are referred to as a first storage tank (T1), a second storage tank (T2), a third storage tank (T3), and a fourth storage tank (T4) in this order.

The manifolds are respectively provided with a liquid manifold for liquid fluid flow and a gas manifold for gaseous fluid flow, but only the liquid manifold (L) necessary for explaining the present embodiment is shown in fig. 1 to 5.

The fluid delivery tube includes: a Liquid Line (LL) arranged to transport liquid LNG between the manifold (L) and LNG storage tanks (T1, T2, T3, T4); a Stripping Line (SL); and a Gas Line (GL) for conveying gaseous natural gas.

The Liquid Line (LL) and the gas Stripping Line (SL) are connected via a manifold (L) and a liquid cross-Line (LC).

When LNG is unloaded from the LNG storage tanks (T1, T2, T3, T4) through the manifold (L) and is loaded into the LNG storage tanks (T1, T2, T3, T4) through the manifold (L), LNG may be transported through the Liquid Line (LL).

Additionally, LNG may flow along the Stripping Line (SL) when the LNG is transported for the purpose of injecting the LNG to the LNG storage tanks (T1, T2, T3, T4) through the manifold (L) and for the purpose of stripping the LNG in the LNG storage tanks (T1, T2, T3, T4).

The ship of the present embodiment further includes a line branching from the Liquid Line (LL) toward each of the LNG storage tanks (T1, T2, T3, and T4). More specifically, the method comprises the following steps: a first liquid line (LL1) branching from the Liquid Line (LL) to a first storage tank (T1); a second liquid line (LL2) branching from the Liquid Line (LL) to a second storage tank (T2); a third liquid line (LL3) branching from the Liquid Line (LL) to a third storage tank (T3); and a fourth liquid line (LL4) branching off from the Liquid Line (LL) to a fourth storage tank (T4).

The first to fourth liquid lines (LL1, LL2, LL3, and LL4) extend to the inner bottom of the LNG storage tanks (T1, T2, T3, and T4), respectively.

Additionally, a line branching from the Stripping Line (SL) toward each LNG storage tank (T1, T2, T3, and T4) is included. More specifically, the method comprises the following steps: a first stripping line (SL1) branching from the Stripping Line (SL) to a first storage tank (T1); a second stripping line (SL2) branching from Stripping Line (SL) to a second storage tank (T2); a third stripping line (SL3) branching from the Stripping Line (SL) to a third storage tank (T3); and a fourth stripping line (SL4) branching from the Stripping Line (SL) to a fourth storage tank (T4).

First through fourth stripping lines (SL1, SL2, SL3, and SL4) are connected through liquid or gas domes of LNG storage tanks (T1, T2, T3, and T4), respectively, and are connected to nozzles installed at the top of the tanks. That is, LNG transferred to the LNG storage tanks (T1, T2, T3, and T4) through the first to fourth stripping lines (SL1, SL2, SL3, and SL4) is jet-supplied from the top of the tanks toward the bottom.

In addition, the lengths of the first through fourth stripping lines (SL1, SL2, SL3, and SL4) may further extend to the inner bottom of the LNG storage tanks (T1, T2, T3, and T4), respectively.

The Gas Line (GL) of the present embodiment connects the boil-off gas processing unit and the LNG storage tanks (T1, T2, T3, T4), and although fig. 1 to 5 show only the Gas Line (GL) through which the boil-off gas discharged from the LNG storage tanks (T1, T2, T3, T4) flows, a vapor line may be further included to flow the gaseous natural gas between the LNG storage tanks (T1, T2, T3, T4) and the manifold and the boil-off gas processing unit.

The Gas Line (GL) includes a branch line connected from the gas dome of each LNG storage tank (T1, T2, T3, and T4) to the boil-off gas processing unit. More specifically, the method comprises the following steps: a first gas line (GL1) branched from the Gas Line (GL) to a first storage tank (T1); a second gas line (GL2) branched from the Gas Line (GL) to a second storage tank (T2); a third gas line (GL3) branching from the Gas Line (GL) to a third storage tank (T3); and a fourth gas line (GL4) branching from the Gas Line (GL) to a fourth storage tank (T4).

In addition, although not shown in the drawings, the boil-off gas treatment unit may include: a boil-off gas fuel supply unit for compressing boil-off gas generated in the LNG storage tanks (T1, T2, T3, and T4) to supply the boil-off gas as engine fuel; a reliquefaction unit for reliquefying the boil-off gas and recovering the reliquefied gas to LNG storage tanks (T1, T2, T3, T4); and the gas combustion unit is used for combusting and treating the evaporation gas.

In addition, the boil-off gas processing unit further includes: a compressor (100) pressurizing boil-off gas generated in the LNG storage tanks (T1, T2, T3, and T4); and a heater (200) for heating the evaporation gas compressed by the compressor (100).

In addition, although not shown in the drawings, the first to fourth gas lines (GL1, GL2, GL3, GL4) may be respectively connected to an exhaust tower (VM) that discharges the evaporation gas into the atmosphere. That is, the boil-off gas may be discharged through a discharge tower (VM) for treatment, if necessary.

In addition, the liquefied gas supply system according to the present embodiment further includes a second connection line (CL2) for connecting the Liquid Line (LL) and the exhaust tower (VM).

The second connecting line (CL2) of the present embodiment connects the Liquid Line (LL) and the exhaust tower (VM). In addition, the second connection line (CL2) may also connect the Liquid Line (LL) and the gas dome of the first storage tank (T1).

The above-described configuration is generally a basic configuration installed in an LNG ship, and the present embodiment provides a method in which boil-off gas generated when LNG is supplied from an LNG tanker to the ship of the present embodiment can be processed on the ship without being returned to the LNG tanker, using the above-described basic configuration.

In the embodiments described later, although the description is based on the supply of LNG to the fourth storage tank (T4), the description is not limited thereto, and even if the description thereof is omitted, it can be understood that the description is equally applicable to the case where LNG is supplied to LNG storage tanks (T1, T2, T3) which are other objects to be cooled or supplied with LNG, only the objects thereof may be changed.

According to the present embodiment, it is possible to simultaneously perform the cooling process and the replacement process of the plurality of LNG storage tanks (T1, T2, T3, T4), and simultaneously perform the supply process and the replacement process.

For example, any one of the storage tanks that has completed the replacement process is cooled, and the boil-off gas generated when the storage tank is cooled is heated and then supplied as the replacement gas to the other storage tank.

Further, LNG may be supplied to a storage tank that has been cooled, and boil-off gas generated when LNG is supplied may be heated and supplied as replacement gas to another storage tank.

First, an initial cooling method of the LNG storage tanks (T1, T2, T3, T4) will be described with reference to fig. 2 and 3, and in the present embodiment, a cooling method will be described with reference to the fourth storage tank (T4) as a storage tank to be cooled, as a representative example.

The vessel according to the present embodiment is connected to the LNG filling vessel via a manifold (L). LNG injected and supplied along a liquid cross Line (LC), a Stripping Line (SL), and a fourth stripping line (SL4) for cooling the fourth storage tank (T4) is injected and supplied from the LNG refueling vessel to the fourth storage tank (T4).

When the LNG spray for cooling is supplied to the fourth storage tank (T4), a large amount of boil-off gas is generated in the fourth storage tank (T4). At this time, the evaporation gas generated in the fourth storage tank (T4) is supplied to the third storage tank (T3), which is a replacement process target, through the fourth gas line (GL4), the Gas Line (GL), and the third gas line (GL3) as a gas for replacement. Thus, the replacement process of the third storage tank (T3) may be performed while the cooling process of the fourth storage tank (T4) is performed.

In addition, the evaporation gas discharged from the fourth storage tank (T4) may be compressed in a compressor (100), heated in a heater (200), and then supplied as a replacement gas to the third storage tank (T3).

For example, for an 173,400M3 grade LNG carrier, the replacement process for each storage tank takes approximately 6 hours and uses approximately 6-8MT/hr of gas. According to the present embodiment, the boil-off gas discharged from the storage tank for cooling, in which the cooling process is performed, is heated by using the heater (200), which is a basic device mounted on the ship, and is supplied as the replacement gas to the storage tank for replacement, in which the replacement process is to be performed.

That is, according to the embodiment of the present invention, while any one of the cooling storage tanks (T4) is cooled, the replacement process of the replacement storage tank (T3) adjacent to the cooling storage tank (T4) that is being cooled may be performed.

As described above, the empty tank is filled with the inert gas due to the drying and safety problems of the empty tank, and as described above, when the replacement gas is supplied to the third storage tank (T3), the inert gas filled in the third storage tank (T3) is pushed out and discharged through the third liquid line (LL 3).

According to the present embodiment, when the replacement process of the third storage tank (T3) is performed while the cooling process of the fourth storage tank (T4) is performed, the inert gas is discharged from the third storage tank (T3) through the third liquid line (LL 3).

The inert gas discharged along the third liquid line (LL3) is fed along the Liquid Line (LL) and the second connecting line (CL2) to the exhaust gas column (VM).

That is, LNG for cooling is supplied to the fourth storage tank (T4) using the Liquid Line (LL), and at the same time, inert gas is sent to the exhaust tower (VM) from the liquid line.

On the other hand, as shown in fig. 2 and 3, the boil-off gas generated when LNG is supplied from the LNG tanker to the ship may be treated in the ship without being returned to the LNG tanker by using the basic configuration and the additional configuration.

According to the present embodiment, as an additional configuration, it is also possible to include: a first connection line (CL1) that connects a liquid branch line (LL1, LL2, LL3, LL4) that branches from the liquid line LL and is connected to each storage tank (T1, T2, T3, T4) so as to bypass an Isolation Valve (IV) (described later); and an Isolation Valve (IV) provided in the stern-side Liquid Line (LL) at the position where the first connection line (CL1) is connected to the Liquid Line (LL) to shut off the flow of the front and rear ends.

When the first connection line (CL1) is further included, the inert gas discharged along the third liquid line (LL3) may be delivered to the exhaust gas tower (VM) along the first connection line (CL1), the Liquid Line (LL), and the second connection line (CL 2).

The first connection line (CL1) and the second connection line (CL2) may not be connected with the Liquid Line (LL), but may be directly connected from the third liquid line (LL3) to the exhaust gas tower (VM). At this time, the total length of the connecting lines (CL1 and CL2) is 50m at the maximum as a 200A-standard calandria in accordance with a 173K-class ship.

For example, the first connection line (CL1) connects the rear ends of the Isolation Valves (IV) provided in the third liquid line (LL3) and the Liquid Line (LL).

An Isolation Valve (IV) is installed between the location where the liquid cross Line (LC) intersects the Liquid Line (LL) and the location where the LNG storage tank (T4) branches off from the intersection to the first mating LNG storage tank.

In addition, an Isolation Valve (IV) is installed between a point where the first connection line (CL1) is connected to the Liquid Line (LL) and a point where it is connected to the liquid cross Line (LC).

That is, LNG for cooling may be supplied to the fourth storage tank (T4) using the Liquid Line (LL), and at the same time, inert gas may be delivered to the exhaust tower (VM) through the Liquid Line (LL). At this time, the Isolation Valve (IV) can be closed, and the flow of the front end and the rear end of the Liquid Line (LL) can be shut off with the Isolation Valve (IV) as a reference.

Meanwhile, as shown in fig. 3, the Isolation Valve (IV) may be further provided at a point where the fluid cross Line (LC) and the fluid line (LL) are connected, in which case the Isolation Valve (IV) may be provided as a three-way valve.

When the Isolation Valve (IV) is set as a three-way valve, as shown in fig. 3, the fourth storage tank (T4) to be cooled is cooled, and the replacement process of the third storage tank (T3) to be replaced is performed, as described above, the side of the Isolation Valve (IV) that is communicated with the gas discharge tower (VM) toward the third storage tank (T3) is opened, and the side that is communicated with the liquid cross-Line (LC) may be closed to prevent mutual communication.

In this way, when the replacement process of the third storage tank (T3) is performed while cooling the fourth storage tank (T4), the Isolation Valve (IV) may be controlled to place the liquid cross-Line (LC) in communication with the gas Stripping Line (SL) and to place the liquid cross-Line (LC) in non-communication with the Liquid Line (LL).

Next, referring to fig. 4 and 5, a method of supplying LNG to a ship according to the present embodiment will be described, and in the present embodiment, a method of supplying LNG to a fourth storage tank (T4) will be described as a representative example.

For example, after the replacement process and the cooling process are completed, LNG is supplied to any one of the storage tanks to be supplied that are to receive LNG, and boil-off gas generated in the storage tank to be supplied during the LNG supply is heated and then supplied as replacement gas to another storage tank to be replaced.

The amount of boil-off gas generated while the cooling process of the above-described fourth storage tank (T4) was carried out was about 120 tons/hr, which was sufficient to complete the replacement process of the third storage tank (T3). In addition, this amount is also sufficient to perform a part of the replacement process of another storage tank, for example, the second storage tank (T2), after the replacement process of the third storage tank (T3) is completed.

Therefore, the embodiment of the present invention, which will be described later, will be described by taking as an example the replacement process of the second storage tank (T2) using boil-off gas generated in the fourth storage tank (T4) in the case where LNG is supplied to the fourth storage tank (T4) after the cooling process is finished.

That is, substantially as described above, when the cooling process of the fourth storage tank (T4) is carried out, the replacement process of the immediately adjacent storage tank, i.e., the third storage tank (T3), is also completed. Thereafter, when LNG is supplied to the fourth storage tank (T4) having completed the cooling process, boil-off gas generated in the fourth storage tank (T4) may be used to perform a replacement process of the second storage tank (T2) and/or the first storage tank (T1), that is, it may be used to perform a replacement process of another storage tank.

In the present embodiment, the Isolation Valve (IV) functions to cut off the flow direction of LNG and the flow direction of the replacement gas from each other in order to supply boil-off gas discharged from the fourth storage tank (T4) as the replacement gas to the second storage tank (T2) or the first storage tank T1 when LNG is supplied to the fourth storage tank (T4) where cooling is completed.

The vessel according to the present embodiment is connected to the LNG filling vessel via a manifold (L). LNG for test runs supplied from the LNG tanker to the fourth storage tank (T4) is supplied to the fourth storage tank (T4) along the liquid cross Line (LC), the Liquid Line (LL), and the fourth liquid line (LL 4).

When LNG is supplied to the fourth storage tank (T4), a large amount of boil-off gas is generated in the fourth storage tank (T4). At this time, the boil-off gas generated in the fourth storage tank (T4) is supplied to the second storage tank (T2) through the fourth gas line (GL4), the Gas Line (GL), and the second gas line (GL2) to be used as a replacement gas, whereby the replacement process of the second storage tank (T2) can be performed while the process of supplying LNG to the fourth storage tank (T4) is performed.

In addition, the boil-off gas discharged from the fourth storage tank (T4) may be compressed in a compressor (100), heated in a heater (200), and then supplied as the replacement gas for the second storage tank (T2).

That is, according to the embodiment of the present invention, while supplying LNG to any one storage tank to be supplied (T4), it is also possible to perform a replacement process of another storage tank to be replaced (T2), which is another storage tank to be replaced (T2) other than the storage tank to be replaced (T3) in which the replacement process is completed while performing a cooling process before the supply process of the storage tank to be supplied (T4) and the storage tank to be supplied (T4).

As described above, the empty tank is filled with the inert gas due to the drying and safety problems of the empty tank, and when the replacement gas is supplied to the second storage tank (T2) as described above, the inert gas filled inside is pushed out and discharged through the liquid line (LL 2).

According to the present embodiment, when the replacement process of the second storage tank (T2) is performed while LNG is supplied to the fourth storage tank (T4), inert gas is discharged from the second storage tank (T2) through the second liquid line (LL 2).

The inert gas discharged along the second liquid line (LL2) is sent to the exhaust gas column (VM) along the Liquid Line (LL) and the second connecting line (CL 2).

That is, while LNG is supplied to the fourth storage tank (T4) which is the storage tank on the stern side by the Liquid Line (LL), the inert gas is sent to the exhaust tower (VM) through the Liquid Line (LL) connected to the bow side with reference to the Isolation Valve (IV).

At this time, the Isolation Valve (IV) is in a closed state to shut off the flow of the Liquid Line (LL) on the stern side and the liquid line LL on the bow side based on the Isolation Valve (IV).

In addition, as shown in fig. 5, the Isolation Valve (IV) may be provided at a point where the liquid cross Line (LC) and the Liquid Line (LL) are connected. In this case, the Isolation Valve (IV) may be provided as a three-way valve.

As shown in fig. 5, when the Isolation Valve (IV) is set to the three-way valve, LNG is supplied to the storage tank to be supplied, i.e., the fourth storage tank (T4), as described above, and the Isolation Valve (IV) is controlled to communicate the liquid cross Line (LC) with a portion of the Liquid Line (LL) and not communicate the liquid cross Line (LC) with the gas Stripping Line (SL) when the replacement process of the storage tank to be replaced, i.e., the second storage tank (T2) is performed.

However, the liquid cross Line (LC) and the Liquid Line (LL) are communicated only with the storage tank to be supplied, i.e., the fourth storage tank (T4), and are not communicated with the storage tank to be replaced, i.e., the second storage tank (T2), under the control of the Isolation Valve (IV).

In other words, when the replacement process of the second storage tank (T2) is performed while LNG is supplied to the fourth storage tank (T4), although the supply of LNG to the fourth storage tank (T4) and the discharge of inert gas from the second storage tank (T2) are both completed through the Liquid Line (LL), the Isolation Valve (IV) shuts off the path of LNG flowing from the manifold (L) to the fourth storage tank (T4) and the path of inert gas flowing from the second storage tank (T2) to the gas vent tower (VM), with reference to the isolation valve IV), to be isolated from each other.

Next, a marine liquefied gas fuel supply system and method according to an embodiment of the present invention will be described with reference to fig. 6 to 10.

A ship according to an embodiment of the present invention includes: two or more LNG fuel tanks (T1 and T2); a manifold (L) for connecting a ship or a receiving station (e.g., an LNG refueling ship) supplying LNG to LNG fuel tanks (T1 and T2); and a fluid transfer pipe for connecting the LNG fuel tanks (T1, T2) with the manifold (L).

The fluid delivery tube includes: a liquefied gas line that supplies LNG from the LNG supply vessel to any one of two or more LNG fuel tanks (T1 and T2); a gas discharge line for discharging boil-off gas generated by supplying LNG to any one of the LNG fuel tanks; and a gas supply line for supplying boil-off gas to one or more other LNG storage tanks.

In the present embodiment described later, the liquefied gas line may refer to a Liquid Line (LL), liquid branch lines (LL1, LL2), a Stripper Line (SL), and stripper branch lines (SL1, SL 2).

In addition, the gas discharge line may refer to a Gas Line (GL), gas branch lines (GL1 and GL2), and a Connection Line (CL), or the gas discharge line may be a Liquid Line (LL) and liquid branch lines (LL1 and LL2) when gas flows along the Liquid Line (LL) and the liquid branch lines (LL1 and LL 2).

In addition, the gas supply line may refer to a Gas Line (GL) and gas branch lines (GL1 and GL 2).

In the ship of the present embodiment, a plurality of LNG storage tanks may be provided, and the plurality of LNG storage tanks may include two or more LNG fuel tanks (T1 and T2), and may further include one or more LNG cargo tanks if the ship is an LNG carrier.

In the present embodiment, the ship is connected to an LNG refueling ship and receives LNG from the LNG refueling ship to LNG fuel tanks (T1 and T2) through a manifold, that is, a method of processing boil-off gas at the time of LNG refueling will be described as an example.

In addition, in one embodiment of the present invention, in order to fill a ship, LNG for initial cooling of an LNG storage tank or for commissioning is supplied from an LNG filling ship, or LNG fuel is supplied (filled) as an example. However, the present invention is not limited thereto, and in an LNG ship provided with two or more LNG tanks, for example, in supplying LNG to an LNG fuel tank of an LNG fuel ship or supplying LNG to an LNG fuel tank, etc., it may be variously applied in any case.

In addition, although not shown in the drawings, the ship according to the present embodiment may include: a main engine for generating propulsion energy using LNG stored in LNG fuel tanks (T1 and T2) as fuel; a power generation engine for generating electric power using LNG stored in LNG fuel tanks (T1 and T2) as fuel; a fuel supply unit for supplying LNG stored in LNG fuel tanks (T1 and T2) or boil-off gas generated by natural vaporization of the LNG to the main engine and the power generation engine to be used as fuel; a reliquefaction unit for reliquefying the boil-off gas and recovering the reliquefied boil-off gas to LNG fuel tanks (T1 and T2); and a gas treatment unit (100, 200) for treating the boil-off gas or the gas discharged from the engine.

In addition, the LNG fuel tanks (TI and T2) may be provided with two or more, and in the present embodiment, as shown in fig. 6 to 10, a ship provided with two LNG fuel tanks (T1 and T2) is shown as an example.

As described above, in the present embodiment, the two LNG fuel tanks (T1 and T2) are provided as an example, but the present invention is not limited thereto. In addition, in the present embodiment, the LNG fuel tanks mounted on the bow to the stern are referred to as a first fuel tank (T1) and a second fuel tank (T2) in this order.

The manifolds include a liquid manifold for flowing a liquid fluid and a gas manifold for flowing a gaseous fluid, respectively, but fig. 6 to 10 only show the liquid manifold (L) necessary for explaining the present embodiment.

The fluid delivery tube includes: a Liquid Line (LL) arranged to convey liquid LNG between the manifold (L) and the LNG fuel tanks (T1, T2); a Stripping Line (SL); and a Gas Line (GL) for conveying gaseous natural gas.

The Liquid Line (LL) and the gas Stripping Line (SL) are connected to the liquid cross-over Line (LC) via a manifold (L).

LNG may be transferred through the Liquid Line (LL) when unloading LNG from the LNG tanks (T1 and T2) through the manifold (L), and when supplying LNG to the LNG tanks (T1 and T2) through the manifold (L).

In addition, LNG may flow along the Stripping Line (SL) when the LNG is delivered for the injection of LNG to the fuel tanks (T1 and T2) through the manifold (L) and for the stripping of LNG in the LNG fuel tanks (T1) and (T2).

The ship of the present embodiment further includes a liquid branch line branching from the Liquid Line (LL) toward each of the LNG fuel tanks (T1 and T2). More specifically, the method comprises the following steps: a first liquid line (LL1) branching from the Liquid Line (LL) to a first fuel tank (T1); and a second liquid line (LL2) branching from the Liquid Line (LL) to the second fuel tank (T2).

The first to second liquid lines (LL1 and LL2) may extend to the inner bottom surfaces of the LNG fuel tanks (T1 and T2), respectively.

In addition, a stripping branch line branching from the Stripping Line (SL) toward each LNG fuel tank (T1 and T2) is also included. More specifically, the method comprises the following steps: a first stripping line (SL1) branching from the Stripping Line (SL) to a first fuel tank (T1); a second stripping line (SL2) branching from the Stripping Line (SL) to a second fuel tank (T2).

The first stripping line (SL1) and the second stripping line (SL2) are connected through the liquid dome or the gas dome of the LNG fuel tanks (T1 and T2), respectively, and are connected to nozzles installed at the top of the tanks.

That is, LNG delivered to the LNG fuel tanks (T1 and T2) through the first to second stripping lines (SL1, SL2) may be spray-supplied from the top of the tank to the bottom thereof.

In addition, the lengths of the first and second stripping lines (SL1, SL2) may further extend to the bottom of the interior of the LNG fuel tanks (T1, T2), respectively.

The Gas Line (GL) of the present embodiment connects the boil-off gas handling unit with the LNG fuel tanks (T1 and T2), and fig. 6 to 10 show only the Gas Line (GL) through which the boil-off gas discharged from the LNG fuel tanks (T1 and T2) flows, but may further include a boil-off line such that the gaseous natural gas flows between the LNG fuel tanks (T1, T2) and the manifold and the boil-off gas handling unit.

The Gas Line (GL) includes a gas branch line connected from a gas dome in each LNG fuel tank (T1 and T2) to the boil-off gas processing unit. More specifically, the method comprises the following steps: a first gas line GL1 branched from the Gas Line (GL) to the first fuel tank (T1); and a second gas line (GL2) branched from the Gas Line (GL) to the second fuel tank (T2).

In addition, although not shown in the drawings, the boil-off gas treatment unit may include: a boil-off gas fuel supply unit for compressing boil-off gas generated in the LNG fuel tanks (T1 and T2) to supply the boil-off gas as engine fuel; a reliquefaction unit which reliquefies the boil-off gas and recovers the reliquefied boil-off gas into LNG fuel tanks (T1 and T2); and the gas combustion unit is used for combusting and treating the evaporation gas.

In addition, the boil-off gas treatment unit includes: a compressor (100) for pressurizing boil-off gas generated in the LNG fuel tanks (T1 and T2); and a heater (200) for heating the evaporation gas compressed by the compressor (100).

In addition, although not shown in the drawings, the first gas line (GL1) to the second gas line (GL2) may be respectively connected to an exhaust tower (VM) that discharges the evaporation gas into the atmosphere. That is, if necessary, the treatment may be performed by discharging the boil-off gas through an exhaust tower (VM).

In addition, the liquefied gas fuel supply system of a ship according to the present embodiment further includes a Connection Line (CL) for connecting the Liquid Line (LL) and the exhaust tower (VM).

The Connection Line (CL) of the present embodiment connects the Liquid Line (LL) and the exhaust tower (VM). In addition, the Connecting Line (CL) may also connect the Liquid Line (LL) and the gas dome of the first fuel tank (T1).

The above-described configuration is generally a basic configuration to be installed on an LNG ship, and the present embodiment provides a method by which boil-off gas generated when LNG is supplied from an LNG tanker to the ship of the present embodiment can be processed on the ship without being returned to the LNG tanker, using the above-described basic configuration.

In the embodiment described later, although the explanation is based on the supply of LNG to the first fuel tank (T1), the explanation is not limited to this, and although the explanation is omitted, it is also understood that the explanation may be omitted, and the explanation may be similarly applied to the case where LNG is supplied to other target LNG fuel tanks (T1 and T2) to be cooled or to be supplied with LNG, only the target thereof may be changed.

According to the present embodiment, the cooling process and the replacement process of two or more LNG fuel tanks (T1 and T2) may be simultaneously performed, and the supply process and the replacement process may be simultaneously performed.

For example, any one of the fuel tanks (T1) that have completed the replacement process is cooled, and the vapor gas generated when the fuel tank is cooled is heated and then supplied as the replacement gas to the other fuel tank (T2).

Further, LNG may be supplied to a fuel tank (T1) in which cooling is completed, and the boil-off gas generated during LNG supply may be heated and supplied as replacement gas for another fuel tank (T2).

A method of cooling the LNG fuel tanks (T1 and T2) will be described with reference to fig. 7 and 8, and in the present embodiment, the method of cooling will be described with the first fuel tank (T1) as the fuel tank to be cooled, as a representative example.

The vessel according to the present embodiment is connected to the LNG filling vessel via a manifold (L). A first fuel tank (T1) is injected from an LNG tanker with a supply of LNG for cooling, the LNG being injected along a liquid cross-over Line (LC), a Stripper Line (SL) and a first stripper line (SL 1).

When LNG for cooling is jet-supplied to the first fuel tank (T1), a large amount of boil-off gas is generated in the first fuel tank (T1). At this time, the vaporization gas generated at the first fuel tank (T1) is supplied to the second fuel tank (T2) to be replaced through the first gas line (GL1), the Gas Line (GL), and the second gas line (GL2) as a gas for replacement. Thus, the replacement process of the second fuel tank (T2) can be performed simultaneously with the cooling process of the first fuel tank (T1).

In addition, the evaporation gas discharged from the first fuel tank (T1) may be compressed in the compressor (100), heated in the heater (200), and then supplied as replacement gas to the second fuel tank (T2).

For example, in the case of an 173,400M3 grade LNG carrier, the replacement process for each fuel tank takes approximately 6 hours and the gas used is approximately 6-8 MT/hr. According to the present embodiment, the boil-off gas discharged from the first fuel tank (T1) in which the cooling process is performed is heated by using the heater (200), which is a basic configuration mounted on the ship, and is supplied as the replacement gas to the second fuel tank (T2) in which the replacement process is to be performed.

That is, according to the embodiment of the invention, while any one of the fuel tanks to be cooled (T1) is cooled, the replacement process of the fuel tank to be replaced (T2) adjacent to the fuel tank to be cooled (T1) to be cooled can be performed.

As described above, the inert gas is filled thereto due to the drying of the empty tank and the safety problem, and as described above, when the replacement gas is supplied to the second fuel tank (T2), the inert gas filled in the second fuel tank (T2) is pushed out and discharged through the second liquid line (LL 2).

According to the present embodiment, when the replacement process of the second fuel tank (T2) is performed simultaneously with the cooling process of the first fuel tank (T1), the inert gas is discharged from the second fuel tank (T2) through the second liquid line (LL 2).

The inert gas discharged along the second liquid line (LL2) is fed along the Liquid Line (LL) and the Connecting Line (CL) to the exhaust gas column (VM).

That is, LNG for cooling is supplied to the first fuel tank (T1) using the Liquid Line (LL), and at the same time, inert gas discharged from the second fuel tank (T2) is delivered to the exhaust tower (VM) using the Liquid Line (LL).

As shown in fig. 7 and 8, the boil-off gas generated when LNG is supplied from the LNG tanker to the ship may be processed in the ship without being returned to the LNG tanker by using the basic configuration and the additional configuration.

According to the present embodiment, as an additional configuration, an Isolation Valve (IV) installed in the Liquid Line (LL) to shut off the flow of the front and rear ends may be further included.

The Connecting Line (CL) may not be connected to the Liquid Line (LL), but may be connected directly from the liquid branch line to the exhaust gas column (VM). At this time, the total length of the Connecting Line (CL) is 50m at the maximum as a 200A standard pipe using a 173K class ship as a standard.

The Isolation Valve (IV) of the present embodiment is installed at a point where the liquid cross Line (LC) intersects the Liquid Line (LL), or between a point where any one of the liquid branch lines branches off to any one of the LNG fuel tanks (T1, T2).

In the drawings of the present embodiment, it is shown as an example that the Isolation Valve (IV) is provided between the point where the liquid cross-over Line (LC) and the Liquid Line (LL) intersect and the point where the second liquid line (LL2) branches off from the Liquid Line (LL), or at the point where the liquid cross-over Line (LC) and the Liquid Line (LL) intersect with the Liquid Line (LL).

That is, LNG may be supplied to the first fuel tank (T1) using the Liquid Line (LL) or the Stripping Line (SL), while inert gas is delivered to the vent tower (VM) through the Liquid Line (LL). At this time, the Isolation Valve (IV) may be closed, and the flow of the front end and the rear end of the Liquid Line (LL) may be cut off based on the Isolation Valve (IV) so that the inert gas does not flow to the first fuel tank (T1).

Meanwhile, as shown in fig. 8, when the Isolation Valve (IV) is disposed at a place where the liquid cross Line (LC) and the Liquid Line (LL) are connected, the Isolation Valve (IV) may be disposed as a three-way valve.

As shown in fig. 8, when the Isolation Valve (IV) is set to the three-way valve, as described above, the first fuel tank (T1) to be cooled is cooled, and the replacement process is performed on the second fuel tank (T2) to be replaced, the Isolation Valve (IV) is opened toward the side of the second fuel tank (T2) communicating with the exhaust tower (VM), and the side communicating with the liquid cross Line (LC) may be closed to prevent the communication with each other.

As described above, when the cooling process of the first fuel tank (T1) and the replacement process of the second fuel tank (T2) are simultaneously performed, the Isolation Valve (IV) may be controlled to communicate the liquid cross-over Line (LC) and the gas Stripping Line (SL) and not to communicate the liquid cross-over Line (LC) and the Liquid Line (LL).

Next, referring to fig. 9 and 10, a method of supplying LNG to the ship of the present embodiment will be described, and in the present embodiment, a method of supplying LNG to the first fuel tank (T1) will be described as a representative example.

For example, after the replacement process and the cooling process are completed, LNG may be supplied to any one of the fuel tanks that are to receive LNG, and the boil-off gas generated in the fuel tank to be supplied during the supply of LNG may be heated and supplied as replacement gas to another fuel tank to be replaced.

The amount of the boil-off gas generated when the above-described cooling process of the first fuel tank (T1) is performed is about 120 tons/hour, which is sufficient to complete the replacement process of the second fuel tank (T2). In addition, after the replacement process of the second fuel tank (T2) is completed, a replacement process of another fuel tank or cargo tank to be replaced may be performed.

In the embodiment of the present invention described below, the replacement process of the second fuel tank (T2) using the boil-off gas generated in the first fuel tank (T1) when LNG is supplied to the first fuel tank (T1) has been described as an example, but substantially as described above, when the cooling process of the first fuel tank (T1) is performed, the boil-off gas generated in the first fuel tank (T1) may be used to perform the replacement process of a fuel tank other than the fuel tank or the LNG storage tank, which has been replaced when the first fuel tank (T1) is cooled.

In the present embodiment, the Isolation Valve (IV) functions to shut off the flow direction of LNG and the flow direction of replacement gas from each other in order to transfer boil-off gas discharged from the first fuel tank (T1) as replacement gas to the second fuel tank (T2) or other LNG storage tanks when LNG is supplied to the first fuel tank (T1) where cooling is completed.

The vessel according to the present embodiment is connected to the LNG filling vessel via a manifold (L). LNG fuel to be supplied from the LNG tanker to the first fuel tank (T1) is supplied to the first fuel tank (T1) along the liquid cross-Line (LC), the Liquid Line (LL), and the first liquid line (LL 1).

When LNG is supplied to the first fuel tank (T1), a large amount of boil-off gas is generated in the first fuel tank (T1). At this time, the evaporation gas generated in the first fuel tank (T1) is supplied to the second fuel tank (T2) through the first gas line GL1, the Gas Line (GL), and the second gas line (GL2) to be used as the replacement gas, whereby the replacement process of the second fuel tank (T2) can be performed while the process of supplying LNG to the first fuel tank (T1) is performed.

The boil-off gas discharged from the first fuel tank (T1) may be compressed by the compressor (100), heated by the heater (200), and supplied as replacement gas for the second fuel tank (T2).

That is, according to the embodiment of the present invention, while supplying LNG to any one of the fuel tanks (T1) to be supplied, a replacement process of another fuel tank (T2) to be replaced may be performed, the fuel tank (T2) being another fuel tank to be replaced other than the fuel tank that completes the replacement process when cooling is performed before the supply process of the fuel tank (T1) to be supplied and the first fuel tank (T1).

As described above, due to the drying of the empty pipe and the safety problem, when the inert gas is filled in the empty tank and the replacement gas is supplied to the second fuel tank (T2) as described above, the inert gas filled inside is pushed out and discharged through the liquid line (LL 2).

According to the present embodiment, when the replacement process of the second fuel tank (T2) is performed while LNG is supplied to the first fuel tank (T1), inert gas is discharged from the second fuel tank (T2) through the second liquid line (LL 2).

The inert gas discharged along the second liquid line (LL2) is sent to the exhaust gas tower (VM) along the Liquid Line (LL) and the Connecting Line (CL).

For example, LNG is supplied to a first fuel tank (T1) which is a fuel tank on the stern side by a Liquid Line (LL), and an inert gas is sent to an exhaust tower (VM) through the Liquid Line (LL) connected to the bow side with reference to an Isolation Valve (IV).

At this time, the Isolation Valve (IV) is in a closed state to shut off the flow of the Liquid Line (LL) on the stern side and the Liquid Line (LL) on the bow side based on the Isolation Valve (IV).

In addition, as shown in fig. 10, the Isolation Valve (IV) may be provided at a point where the fluid cross Line (LC) and the fluid line (LL) are connected, in which case the Isolation Valve (IV) may be provided as a three-way valve.

Referring to fig. 10, when the Isolation Valve (IV) is set to the three-way valve, as described above, LNG is supplied to the first fuel tank (T1), which is the fuel tank to be supplied, and the replacement process of the second fuel tank (T2), which is the fuel tank to be replaced, the Isolation Valve (IV) is controlled such that the liquid cross Line (LC) communicates with the Liquid Line (LL) on the side where the first liquid line (LL1) branches, and does not communicate with the Liquid Line (LL) on the side where the second liquid line (LL2) branches.

However, under the control of the Isolation Valve (IV), the liquid cross Line (LC) and the Liquid Line (LL) communicate only with the side of the fuel tank to be supplied, i.e., the first fuel tank (T1), and do not communicate with the side of the fuel tank to be replaced, i.e., the second fuel tank (T2).

In this way, when the replacement process of the second fuel tank (T2) is performed while supplying LNG to the first fuel tank (T1), although the supply of LNG to the first fuel tank (T1) and the discharge of the inert gas from the second fuel tank (T2) are both accomplished through the Liquid Line (LL), the Isolation Valve (IV) cuts off the path of LNG flowing from the manifold (L) to the first fuel tank (T1) and the path of the inert gas flowing from the second fuel tank (T2) to the exhaust tower (VM) with reference to the Isolation Valve (IV) to be isolated from each other.

As described above, the embodiments according to the present invention are described, and the fact that the present invention can be embodied in other specific forms than the above-described embodiments without departing from the spirit or scope thereof will be apparent to those of ordinary skill in the art. Accordingly, the above-described embodiments should be regarded as illustrative rather than restrictive, and the invention is not to be limited by the foregoing description, but may be modified within the scope of the appended claims along with their full scope of equivalents.

Claims

1. A liquefied gas supply system that supplies liquefied gas from a liquefied gas supply vessel to a vessel including a plurality of liquefied gas storage tanks, comprising:

a liquefied gas line for supplying liquefied gas from the liquefied gas supply vessel to any one of the plurality of liquefied gas storage tanks;

a gas discharge line for discharging a boil-off gas generated by supplying the liquefied gas to the any one of the liquefied gas storage tanks; and

a gas supply line for supplying the boil-off gas to one or more other liquefied gas storage tanks.

2. The liquefied gas supply system according to claim 1,

further comprising:

a heater for heating the evaporation gas discharged along the gas discharge line,

wherein the boil-off gas heated at the heater is supplied to one or more other liquefied gas storage tanks through the gas supply line.

3. The liquefied gas supply system according to claim 1,

the boil-off gas generated when the liquefied gas is supplied to any one of the liquefied gas storage tanks is supplied to the other liquefied gas storage tank.

4. The liquefied gas supply system according to claim 1,

the boil-off gas generated when the liquefied gas is supplied to any one of the liquefied gas storage tanks is supplied to all of the remaining liquefied gas storage tanks.

5. The liquefied gas supply system according to claim 1,

the liquefied gas line, comprising:

a liquid cross line for connecting the liquefied gas supply vessel and the liquefied gas storage tank and transferring liquefied gas from the liquefied gas supply vessel; a liquid line for branching and supplying the received liquefied gas to each liquefied gas storage tank through the liquid cross-line.

6. The liquefied gas supply system according to claim 5,

the liquid line is connected to the liquid supply line,

further comprising one or more isolation valves for isolating the liquid line so that liquefied gas is not supplied to one or more other liquefied gas storage tanks when liquefied gas is supplied through the liquid cross-line.

7. The liquefied gas supply system according to claim 6,

the isolation valve is disposed between a point where the liquid cross line and the liquid line intersect and a point where the isolation valve branches from the point to a first intersected liquefied gas storage tank.

8. The liquefied gas supply system according to claim 1,

the gas supply line for discharging boil-off gas generated when liquefied gas is supplied to any one of the liquefied gas storage tanks and supplying the boil-off gas to the one or more other liquefied gas storage tanks,

discharging gas discharged from a liquefied gas storage tank that receives the boil-off gas, using the liquefied gas line,

further comprising an isolation valve provided in a liquefied gas line between a liquefied gas storage tank that receives liquefied gas through the liquefied gas line and a liquefied gas storage tank that receives the boil-off gas, shutting off the flow of the liquefied gas and the boil-off gas flowing along the liquefied gas line without mixing them.

9. The liquefied gas supply system according to claim 8,

further comprising:

a manifold; and

a cross line for connecting the manifold and a liquefied gas line,

wherein the isolation valve is a three-way valve provided at a point where the crossover line and liquefied gas line intersect.

10. The liquefied gas supply system according to claim 8,

the gas discharged from the liquefied gas storage tank receiving the boil-off gas is an inert gas,

further comprising a connecting line for connecting the liquefied gas line and the gas discharge column,

wherein the inert gas is delivered from the liquefied gas storage tank to the exhaust tower.

11. A liquefied gas supply method of supplying a liquefied gas from a liquefied gas supply vessel to a vessel including a plurality of liquefied gas storage tanks, comprising:

a liquefied gas supply step of supplying liquefied gas from a liquefied gas supply vessel to any one of the plurality of liquefied gas storage tanks;

a boil-off gas discharge step of discharging boil-off gas generated when liquefied gas is supplied to any one of the liquefied gas storage tanks; and

a replacement gas supply step of supplying the boil-off gas discharged from any one of the liquefied gas storage tanks to one or more other liquefied gas storage tanks among the plurality of liquefied gas storage tanks.

12. The liquefied gas supply method according to claim 11,

heating the boil-off gas discharged in the boil-off gas discharge step, and supplying the heated boil-off gas to one or more other liquefied gas storage tanks.

13. The liquefied gas supply method according to claim 11,

14. The liquefied gas supply method according to claim 11,

15. The liquefied gas supply method according to claim 11,

when liquefied gas is supplied to any one of the liquefied gas storage tanks, the liquefied gas is shut off so that liquefied gas is not supplied to one or more other liquefied gas storage tanks.

16. The liquefied gas supply method according to claim 11,

further comprising an inert gas discharge step of discharging the inert gas filled in the liquefied gas storage tank receiving the boil-off gas due to the receipt of the boil-off gas,

wherein the inert gas is discharged through a line that supplies the liquefied gas to the liquefied gas storage tank.

17. The liquefied gas supply method according to claim 16,

the step of exhausting the inert gas is carried out,

further comprising an isolating step of isolating a portion, in which liquefied gas flows to the liquefied gas storage tank, and a portion, in which the inert gas flows, from each other in a line that supplies the liquefied gas to the liquefied gas storage tank.

18. A liquefied gas fuel supply system for a ship that supplies liquefied gas fuel from a liquefied gas supply ship to a liquefied gas fuel ship that includes two or more liquefied gas fuel tanks,

the method comprises the following steps:

a first fuel tank for storing liquefied gaseous fuel; and

a second fuel tank for storing liquefied gaseous fuel,

wherein the liquefied gas fuel is supplied from the liquefied gas supply vessel using a liquid branch line or a gas stripping branch line connected to the first fuel tank, and the boil-off gas discharged from the first fuel tank is supplied as a replacement gas to the second fuel tank.

19. A marine liquefied gas fuel supply system according to claim 18,

further comprising a gas line for conveying the evaporation gas,

the gas line is provided with:

a compressor for compressing the boil-off gas; and

a heater for heating the evaporation gas compressed by the compressor,

thereby compressing and heating the boil-off gas delivered from the first fuel tank to the second fuel tank for supply.

20. A marine liquefied gas fuel supply system according to claim 18,

further comprising:

a liquid line for connecting each of the liquid branch lines; and

an isolation valve provided between a point at which the liquid branch line of the first fuel tank branches from the liquid line and a point at which the liquid branch line of the second fuel tank branches from the liquid line.

21. A marine liquefied gas fuel supply system according to claim 20,

when liquefied gas is supplied to the first fuel tank using the liquid branch line, gas discharged from the second fuel tank is discharged through a liquid branch line connected to the second fuel tank, and the isolation valve is closed.

22. A marine liquefied gas fuel supply system according to claim 21,

further comprising a connecting line for connecting the liquid line and the exhaust column;

when the liquefied gas is supplied to the first fuel tank through the liquid branch line, the gas discharged from the second fuel tank is discharged to the exhaust tower through the liquid line and the connection line.