KR20210082057A - Liquefied Gas Fuel Supply System - Google Patents

Abstract

The present invention relates to a liquefied gas fuel supply system for a ship that can process BOG generated when liquefied gas is supplied to a fuel tank of a ship without returning it.
A liquefied gas fuel supply system for a ship according to the present invention is a system for supplying liquefied gas fuel from a liquefied gas supply ship to a liquefied gas fuel ship including two or more liquefied gas fuel tanks, a first for storing liquefied gas fuel fuel tank; and a second fuel tank for storing the liquefied gas fuel, and at the same time supplying the liquefied gas fuel from the liquefied gas supply vessel using a liquid branch line or a stripping branch line connected to the first fuel tank, the second fuel tank 1 The boil-off gas discharged from the fuel tank is supplied as a replacement gas of the second fuel tank.

Description

Liquefied Gas Fuel Supply System for Ships

The present invention relates to a liquefied gas fuel supply system for a ship that can process boil-off gas generated when liquefied gas fuel is supplied to a fuel tank of a ship without returning it to the outside.

In general, natural gas is produced in a state of liquefied natural gas (LNG) at a production site, and then transported to a gas terminal on land by an LNG carrier.

As the supply of LNG-fueled ships is activated as an alternative measure to solve the environmental pollution problem, the operation of LNG bunkering ships is also increasing. An LNG bunkering vessel is a vessel that directly goes to a ship operating LNG and supplies LNG from an LNG bunkering vessel to an LNG fueled vessel at sea.

Even when supplying LNG from an LNG bunkering vessel to an LNG fueled vessel, a large amount of BOG is generated within the LNG fueled vessel receiving the LNG.

Since the LNG fuel vessel is loaded with cargo, it is not easy to install a pipe to recover BOG, and since BOG is a flammable material, there is a risk of fire or explosion. It is desirable to recover from the vessel and process it in an LNG bunkering vessel.

The LNG fuel tank, which is empty before receiving LNG fuel, is usually filled with an inert gas to prevent gas explosion. That is, a gassing up process of replacing the inert gas in the tank with natural gas is required before storing LNG fuel in an empty LNG fuel tank during the trial operation stage before starting the operation of the LNG fuel vessel or during operation. Do.

In addition, after the replacement process, a cooling down process of lowering the temperature inside the fuel tank may be performed, and then LNG may be supplied to the fuel tank.

On the other hand, during the cool-down process and supply of LNG, a large amount of boil-off gas (excessive BOG) is generated, and the boil-off gas is generally returned to a gas terminal to maintain the pressure inside the tank.

For example, in the cool-down process step, about 4 to 7 MT/hr of BOG is generated, and in the LNG supply step, about 7 to 9 MT/hr of BOG is generated. At the gas terminal, when supplying LNG, about 4 to 9 MT/hr of BOG is returned from the vessel at each stage as described above, and the BOG is re-liquefied and recovered or processed by burning in a GCU (Gas Combustion Unit). .

Technology of supplying LNG for trial operation to several LNG vessels equipped with an LNG fuel tank, for example, an LNG carrier using an LNG bunkering vessel, as well as refueling LNG fuel from the sea to an LNG fuel vessel using such an LNG bunkering vessel. is being actively discussed.

As described above, in order to supply LNG to an LNG fuel tank or an LNG fuel tank, a replacement process and a cool-down process should be preceded. That is, in order to supply LNG to an LNG fuel vessel using an LNG bunkering vessel, the LNG bunkering vessel must be able to directly process the BOG of about 4 to 9 MT/hr recovered from the LNG fuel vessel at each stage.

However, the GCU of the LNG bunkering vessel has limited capacity. In the case of an LNG bunkering vessel that is actually built in Korea with the LNG bunkering function applied, and an LNG bunkering vessel that is actually built by a domestic shipbuilder and is operating in a European port, the GCU capacity is less than 1 ton.

In addition, since the LNG carrier in the trial operation stage is not ready to operate the GCU or reliquefaction device capable of processing BOG, it may be impossible to process BOG in the LNG carrier itself.

As such, in reality, it is impossible to treat all of the BOG generated during cool-down and supply without venting the BOG into the atmosphere.

Accordingly, an object of the present invention is to solve the above-described problem, and it is possible to self-treat BOG generated when supplying LNG to an LNG fuel tank of an LNG fuel ship to an LNG bunkering ship without recovering it to an LNG fuel ship. An object of the present invention is to provide a liquefied gas fuel supply system for ships.

According to one aspect of the present invention for achieving the above object, in a system for supplying liquefied gas fuel from a liquefied gas supply ship to a liquefied gas fuel ship including two or more liquefied gas fuel tanks, storing the liquefied gas fuel a first fuel tank; and a second fuel tank for storing the liquefied gas fuel, and at the same time supplying the liquefied gas fuel from the liquefied gas supply vessel using a liquid branch line or a stripping branch line connected to the first fuel tank, the second A liquefied gas fuel supply system of a ship is provided for supplying the boil-off gas discharged from the first fuel tank as a replacement gas of the second fuel tank through a gas line.

Preferably, the gas line includes a compressor for compressing the boil-off gas; and a heater for heating the boil-off gas compressed by the compressor; may be provided to compress and heat the boil-off gas transferred from the first fuel tank to the second fuel tank and supply it.

Preferably, a liquid line connecting each liquid branch line; and an isolation valve provided between a point where the liquid branch line of the first fuel tank branches from the liquid line and a point where the liquid branch line of the second fuel tank branches off from the liquid line.

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

Preferably, the liquid branch line of the second fuel tank and a first connect line connecting the rear end of the isolation valve; may further include.

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 vent mast through the liquid line and the first connect line. .

The liquefied gas fuel supply system for a ship according to the present invention, when supplying LNG to an LNG fuel tank of an LNG fuel ship, does not recover the boil-off gas generated from the LNG fuel tank to the LNG supplier, but can be self-treated in the LNG fuel ship. can

In particular, when it is desired to supply LNG during the trial operation stage of an LNG fuel vessel or when the LNG fuel tank is empty, the boil-off gas generated during the LNG cool-down process and the LNG supply process is not recovered to the LNG bunkering vessel and is used in the LNG fuel vessel. You can handle it yourself.

Therefore, it is possible to supply LNG to an LNG fueled vessel by using an LNG bunkering vessel at sea.

In addition, it is not necessary to forcibly vaporize the LNG for the replacement process.

In addition, BOG treatment and LNG supply can be performed simultaneously in a vessel supplying LNG.

1 is a conceptual diagram schematically illustrating a liquefied gas fuel supply system for a ship according to an embodiment of the present invention.
2 is a view showing a flow state of a fluid during cool-down of a first fuel tank of a liquefied gas fuel supply system of a ship according to an embodiment of the present invention.
3 is a view showing a fluid flow state during cool-down of the first fuel tank of the liquefied gas fuel supply system of the ship according to another embodiment of the present invention.
4 is a view showing the flow state of the fluid when supplying LNG to the first fuel tank of the liquefied gas fuel supply system of the ship according to an embodiment of the present invention.
5 is a view showing the flow state of the fluid when supplying LNG to the first fuel tank of the liquefied gas fuel supply system of the ship according to another embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objects achieved by the practice 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.

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Here, in adding reference signs to the elements of each drawing, it should be noted that only the same elements are indicated by the same reference signs as possible even if they are indicated on different drawings. In addition, the following examples may be modified in various other forms, and the scope of the present invention is not limited to the following examples.

In an embodiment of the present invention to be described later, liquefied gas may be a liquefied gas fuel capable of transporting the gas by liquefying the gas at a low temperature, for example, LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Gas). Petroleum Gas), liquefied ethylene gas (Liquefied Ethylene Gas), may be a liquefied gas such as liquefied propylene gas (Liquefied Propylene Gas). Alternatively, liquid gas such as liquefied carbon dioxide, liquefied hydrogen or liquefied ammonia may be used. However, in the embodiments to be described later, an example in which LNG, which is a representative liquefied gas fuel, is applied will be described.

In addition, in the embodiment to be described later, the ship is described by taking the case of a LNG carrier that transports liquefied natural gas as cargo, but the present invention is an LNG FSRU (Floating LNG FSRU) equipped with a storage tank for storing liquefied natural gas. Offshore structures such as LNG fuel vessels equipped with liquefied gas storage tanks such as Storage Regasification Unit), LNG FPSO (Floating Production Storage Offloading), and LNG RV (Regasification Vessel), or an engine supplied with liquefied gas as fuel and a liquefied gas fuel tank Or it can be applied to ships.

In addition, in the embodiment to be described later, the storage tank or fuel tank is a concept including all cargo tanks, fuel tanks, etc., regardless of the name, as long as it is a tank for storing liquefied gas.

A system and method for supplying liquefied gas fuel for a ship according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5 .

A ship according to an embodiment of the present invention connects two or more LNG fuel tanks (T1, T2) and a ship or terminal that supplies LNG, such as an LNG bunkering ship, in order to supply LNG to the LNG fuel tanks (T1, T2). and a manifold (L) to be used, and a fluid transfer pipe connecting the LNG fuel tanks (T1, T2) and the manifold.

The fluid transfer pipe includes a liquefied gas line that supplies LNG from an LNG supply vessel to any one of two or more LNG fuel tanks (T1, T2), and a liquefied gas line that supplies LNG to any one of the LNG fuel tanks. and a gas discharge line for discharging BOG generated by supplying the BOG, and a gas supply line for supplying BOG to one or more other LNG storage tanks.

In this embodiment to be described later, the liquefied gas line may mean the liquid line LL and the liquid branch lines LL1 and LL2, the stripping line SL and the stripping branch lines SL1 and SL2.

In addition, the gas discharge line may refer to the gas line GL and the gas branch lines GL1 and GL2 and the connect line CL, or gas along the liquid line LL and the liquid branch lines LL1 and LL2. When is flowing, it may mean the liquid line LL and the liquid branch lines LL1 and LL2.

In addition, the gas supply line may refer to the gas line GL and the gas branch lines GL1 and GL2 .

The ship of this embodiment may be provided with a plurality of LNG storage tanks, and the plurality of LNG storage tanks may include two or more LNG fuel tanks T1 and T2, and, when the ship is an LNG carrier, one or more LNG storage tanks. It may further include a cargo tank.

In this embodiment, the vessel is connected to the LNG bunkering vessel and receives LNG from the LNG bunkering vessel through the manifold to the LNG fuel tanks T1 and T2, that is, a method of processing boil-off gas during LNG bunkering. do it with

In addition, in one embodiment of the present invention, supplying LNG for initial cool-down of an LNG storage tank or LNG for trial operation from an LNG bunkering vessel for the purpose of bunkering of a vessel, or supplying (recharging) LNG fuel is described as an example do. However, the present invention is not limited thereto, and in the case of supplying LNG to an LNG fuel tank of an LNG fuel vessel or supplying LNG to an LNG fuel tank, in an LNG vessel equipped with two or more LNG tanks, supplying LNG to an LNG tank In any case, it can be applied in various ways.

In addition, although not shown in the drawings, the ship according to the present embodiment includes a main engine that generates propulsion energy using LNG stored in the LNG fuel tanks T1 and T2 as a fuel, and the LNG fuel tanks T1 and T2. A power generation engine that generates electric energy by using LNG stored in a fuel cell, and a fuel that supplies boil-off gas generated by natural vaporization of LNG or LNG stored in LNG fuel tanks (T1, T2) as fuel for the main engine and power generation engine It may include a supply unit, a reliquefaction unit for re-liquefying the boil-off gas and recovering it to the LNG fuel tanks T1 and T2, and gas processing units 100 and 200 for processing the boil-off gas or the tripped gas from the engine.

In addition, two or more LNG fuel tanks T1 and T2 may be provided, and in this embodiment, two LNG fuel tanks T1 and T2 are provided as an example as shown in FIGS. 1 to 5 . did.

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

The manifold is separately provided for a liquid in which a liquid fluid flows and a vapor in which a gaseous fluid flows, but only the liquid manifold (L) necessary for explaining this embodiment is shown in FIGS. 1 to 5 .

The fluid transfer pipe is a liquid line (LL) and a stripping line (SL) provided to transfer LNG in a liquid state between the manifold (L) and the LNG fuel tanks (T1, T2), and natural gas in a gaseous state is transferred and a gas line GL provided so as to be possible.

The liquid line LL and the stripping line SL are connected through the manifold L and the liquid crossover line LC.

When unloading LNG from the LNG fuel tanks (T1, T2) through the manifold (L) and when supplying (loading) LNG to the LNG fuel tanks (T1, T2) through the manifold (L) , LNG may be transported through a liquid line (LL).

In addition, when transporting LNG for the purpose of injecting LNG into the LNG fuel tanks (T1, T2) through the manifold (L) and for the purpose of stripping the LNG in the LNG fuel tanks (T1, T2), the stripping line (SL) ) can flow along the LNG.

The ship of this 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 first liquid line LL1 branching from the liquid line LL to the first fuel tank T1 and the second liquid line branching from the liquid line LL to the second fuel tank T2 ( LL2).

The first to second liquid lines LL1 and LL2 may extend to the inner bottom surface of the LNG fuel tanks T1, T2, T3, and T4, respectively.

In addition, it further includes a stripping branch line branching from the stripping line (SL) toward each LNG fuel tank (T1, T2). More specifically, the first stripping line (SL1) branching from the stripping line (SL) to the first fuel tank (T1) and the second stripping line branching from the stripping line (SL) to the second fuel tank (T2) ( SL2).

The first to second stripping lines SL1 and SL2 are respectively connected through the liquid dome or gas dome of the LNG fuel tanks T1 and T2, and are connected to the injection nozzle installed on the upper part of the tank.

That is, the LNG transferred to the LNG fuel tanks T1 and T2 through the first to second stripping lines SL1 and SL2 may be injected and supplied from the upper part of the tank toward the lower part.

In addition, the length of the first to second stripping lines SL1 and SL2 may be further extended to the lower part of the inside of the LNG fuel tanks T1 and T2, respectively.

The gas line GL of this embodiment connects the boil-off gas processing unit and the LNG fuel tanks T1 and T2, and in FIGS. 1 to 5, the gas line through which the boil-off gas discharged from the LNG fuel tanks T1 and T2 flows ( Although only GL) is shown, a vapor line provided so that natural gas in gaseous state flows between the LNG fuel tanks T1 and T2 and the manifold and the boil-off gas processing unit may be further included.

The gas line GL includes a gas branch line connected from the gas dome of each of the LNG fuel tanks T1 and T2 to the boil-off gas processing unit. More specifically, the first gas line GL1 branching from the gas line GL to the first fuel tank T1 and the second gas line branching from the gas line GL into the second fuel tank T2 ( GL2).

In addition, although not shown in the drawings, the BOG processing unit includes a BOG fuel supply unit that compresses BOG generated in the LNG fuel tanks T1 and T2 and supplies it as fuel for the engine, and re-liquefies BOG for LNG fuel. It may include a reliquefaction unit for recovering to the tanks T1 and T2, and a Gas Combustion Unit (GCU) for burning and processing boil-off gas.

In addition, the boil-off gas processing unit, the compressor 100 for pressurizing the boil-off gas generated in the LNG fuel tanks (T1, T2); A heater 200 for heating the boil-off gas compressed by the compressor 100 may be further included.

Also, although not shown in the drawings, the first to second gas lines GL1 and GL2 may be connected to the vent mast VM for discharging BOG to the atmosphere, respectively. That is, if necessary, the boil-off gas may be vented through the vent mast VM for processing.

In addition, the liquefied gas fuel supply system of the ship according to the present embodiment, the liquid line (LL) and the connecting line (CL) for connecting the vent mast (VM); further includes.

The connecting line CL of this embodiment connects the liquid line LL and the vent mast VM. In addition, the connecting line CL may connect the liquid line LL and the gas dome of the first fuel tank T1.

The above-described configurations are generally basic configurations installed in an LNG vessel, and this embodiment utilizes the above-described basic configurations to convert BOG generated when supplying LNG from the LNG bunkering vessel to the vessel of this embodiment into the LNG bunkering vessel. We propose a method that can be disposed of on board the vessel without being returned.

In the embodiment to be described later, the description is based on supplying LNG to the first fuel tank T1, but the present invention is not limited thereto, and even if the description is omitted, other cool-down or LNG supply target LNG fuel tanks T1 and T2 are used. Even when supplying LNG, it will be understood to be applied in the same way by changing only the target.

According to this embodiment, the cool-down process and the substitution process, and the supply process and the substitution process of two or more LNG fuel tanks T1 and T2 may be simultaneously performed.

For example, one of the fuel tanks T1 after the replacement process is cooled down, and the boil-off gas generated while the fuel tank is cooled down is heated and supplied as a replacement gas of the other fuel tank T2.

In addition, LNG may be supplied to the fuel tank T1 after cooling down, and the boil-off gas generated while supplying the LNG may be heated and supplied as a replacement gas of the other fuel tank T2.

First, a method of cooling down the LNG fuel tanks T1 and T2 will be described with reference to FIGS. 2 and 3 , and in this embodiment, a method of cooling down the first fuel tank T1 as a fuel tank to be cooled down is representative. An example will be described.

The vessel according to the present embodiment is connected to the LNG bunkering vessel through the manifold (L). LNG to cool down the first fuel tank (T1) from the LNG bunkering vessel is injected and supplied to the first fuel tank (T1) along the liquid crossover line (LC), the stripping line (SL) and the first stripping line (SL1) do.

When the cooling-down LNG is injected and 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 BOG generated in the first fuel tank T1 is replaced with the second fuel tank T2, which is a replacement process, through the first gas line GL1, the gas line GL, and the second gas line GL2. By supplying the gas with a solvent, the replacement process of the 2nd fuel tank T2 can be implemented simultaneously with implementing the cool-down process of the 1st fuel tank T1.

In addition, the boil-off gas discharged from the first fuel tank T1 may be compressed by the compressor 100 and heated by the heater 200 , and then supplied as a replacement gas of the second fuel tank T2 .

^{In the case of a 173,400M class 3} LNG carrier, the replacement process takes about 6 hours per one fuel tank using about 6 to 8 MT/hr of gas. According to the present embodiment, the second fuel tank to perform the replacement process by heating the boil-off gas discharged from the first fuel tank T1 that performs the cool-down process using the heater 200, which is a basic configuration installed in the ship. It is supplied as a gas for replacement of (T2).

That is, according to an embodiment of the present invention, a replacement fuel tank (T2) adjacent to the cool-down fuel tank (T1) that cools down and cools down any one of the fuel tanks (T1) for cool-down. A substitution step of can be carried out.

As described above, the empty tank is filled with an inert gas for reasons of drying and safety of the tank. In this way, when the replacement gas is supplied to the second fuel tank T2, the second fuel tank T2 is filled inside. The existing inert gas is pushed and discharged through the second liquid line LL2.

According to this embodiment, when performing the replacement process of the second fuel tank T2 simultaneously with the cool-down process of the first fuel tank T1, the inert gas is supplied from the second fuel tank T2 to the second liquid line ( LL2).

The inert gas discharged along the second liquid line LL2 is transferred to the vent mast VM along the liquid line LL and the connecting line CL.

That is, while supplying cool-down LNG to the first fuel tank T1 using the liquid line LL, the inert gas discharged from the second fuel tank T2 is vented using the liquid line LL. It is transferred to the mast (VM).

On the other hand, as shown in FIGS. 2 and 3 , by utilizing additional configurations to the above-described basic configurations, BOG generated when supplying LNG from an LNG bunkering vessel to a vessel is not returned to the LNG bunkering vessel. can also be processed.

According to this embodiment, as an additional configuration, the isolation valve (IV) installed on the liquid line (LL) to block the front and rear flow; may further include.

The connecting line CL may not be connected from the liquid line LL, but may be directly connected from the liquid branch line to the vent mast VM. In this case, the total length of the connecting line CL may be up to 50m as a pipe of 200A standard based on a 173K class vessel.

The isolation valve IV of this embodiment is a point where the liquid crossover line LC meets the liquid line LL or at the point where any one liquid branch line is branched into any one LNG fuel tank T1, T2. installed between branches.

In the drawing of this embodiment, the isolation valve IV is provided between the point where the liquid crossover line LC meets the liquid line LL and the point where the second liquid line LL2 is branched from the liquid line LL. or provided at a point where the liquid crossover line LC and the liquid line LL meet the liquid line LL is illustrated as an example.

That is, while supplying LNG to the first fuel tank T1 using the liquid line LL or the stripping line SL, the inert gas may be transferred to the vent mast VM through the liquid line LL. have. At this time, the isolation valve (IV) is in a closed state to block the flow of the front and rear ends of the liquid line (LL) based on the isolation valve (IV), so that the inert gas does not flow into the first fuel tank (T1). can do.

On the other hand, when the isolation valve IV is provided at the point where the liquid crossover line LC and the liquid line LL are connected as shown in FIG. 3 , the isolation valve IV may be provided as a three-way valve. have.

As shown in FIG. 3 , when the isolation valve IV is provided as a three-way valve, as described above, the cool-down of the first fuel tank T1 that is the cool-down target is performed, and the second fuel tank T2 that is the replacement target. ), the isolation valve (IV) is opened to the side where the second fuel tank (T2) and the vent mast (VM) communicate with each other, and the liquid crossover line (LC) communicates with each other. It can be closed to prevent communication.

In this way, when performing the cooling-down of the first fuel tank T1 and the replacement process of the second fuel tank T2 at the same time, by controlling the isolation valve IV, the crossover line LC and the stripping line SL communicates with each other, and crossover line LC and liquid line LL do not communicate with each other.

Next, a method of supplying LNG to a ship of this embodiment will be described with reference to FIGS. 4 and 5 , and in this embodiment, a method of supplying LNG to the first fuel tank T1 will be described as a representative example.

For example, LNG is supplied to any one fuel tank for supply that is ready to receive LNG by completing the substitution process and the cool-down process, and the boil-off gas generated from the supply fuel tank is heated while supplying the LNG to the other fuel tank. It can also be supplied as a replacement gas for the replacement fuel tank.

The amount of BOG generated while performing the above-described cool-down process of the first fuel tank T1 is about 120 tons/hr, which is sufficient to complete the replacement process of the second fuel tank T2. In addition, after completing the replacement process of the second fuel tank (T2), another replacement target fuel tank or cargo tank replacement process may be performed.

An embodiment of the present invention to be described later exemplifies that when LNG is supplied to the first fuel tank T1, the replacement process of the second fuel tank T2 is performed with the boil-off gas generated in the first fuel tank T1. As described above, although substantially as described above, when the cool-down process of the first fuel tank T1 is performed, the replacement process of the second fuel tank T2, which is an adjacent fuel tank, is completed. After that, when the LNG is supplied to the first fuel tank T1 on which the cool-down process is completed, BOG generated in the first fuel tank T1 is generated in another fuel tank other than the substituted fuel tank during the cool-down of the first fuel tank T1. It can be used to carry out the replacement process of fuel tanks or LNG storage tanks.

In the present embodiment, the isolation valve (IV), when supplying LNG to the first fuel tank (T1), the cool-down is completed, the boil-off gas discharged from the first fuel tank (T1) to the second fuel tank (T2) or or It serves to mutually block the flow direction of the LNG and the flow direction of the replacement gas in order to supply it as a replacement gas for another LNG storage tank.

The vessel according to the present embodiment is connected to the LNG bunkering vessel through the manifold (L). The LNG fuel to be supplied from the LNG bunkering vessel to the first fuel tank T1 is supplied to the fourth fuel tank T1 along the liquid crossover line LC, the liquid line LL, and the first liquid line LL1.

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 boil-off gas generated in the first fuel tank T1 is a gas for replacement of the second fuel tank T2 through the first gas line GL1, the gas line GL, and the second gas line GL2. By supplying, while implementing the process of supplying LNG to the 1st fuel tank T1, the replacement process of the 2nd fuel tank T2 can be implemented.

In addition, the boil-off gas discharged from the first fuel tank T1 may be compressed by the compressor 100 and heated by the heater 200 , and then supplied as a replacement gas of the second fuel tank T2 .

That is, according to an embodiment of the present invention, at the same time as supplying LNG to any one of the fuel tanks for supply (T1), the cooling down before the supply process of the supply fuel tank (T1) and the supply fuel tank (T1) At the same time when performing the process, the substitution process of another fuel tank for substitution (T2) in addition to the fuel tank in which the substitution process has already been completed may be performed.

As described above, the empty tank is filled with an inert gas for reasons of drying and safety of the tank. In this way, when the replacement gas is supplied to the second fuel tank T2, the inert gas filled therein is pushed and the second It is discharged through the liquid line LL2.

According to this embodiment, when supplying LNG to the first fuel tank T1 and performing the replacement process of the second fuel tank T2 at the same time, an inert gas is supplied from the second fuel tank T2 to the second liquid line. (LL2) is discharged.

The inert gas discharged along the second liquid line LL2 is transferred to the vent mast VM along the liquid line LL and the connecting line CL.

For example, while supplying LNG to the first fuel tank T4, which is the stern side fuel tank, using the liquid line LL, the liquid line connected to the bow side based on the isolation valve IV is an inert gas It is transported towards the vent mast (VM).

At this time, the isolation valve (IV) blocks the flow of the stern side liquid line (LL) and the bow side liquid line (LL) based on the isolation valve (IV) to be in a closed state.

On the other hand, the isolation valve IV may be provided at a point where the liquid crossover line LC and the liquid line LL are connected as shown in FIG. 5 , and in this case, the isolation valve IV is a three-way valve. can be provided.

As shown in FIG. 5, when the isolation valve IV is provided as a three-way valve, LNG is supplied to the first fuel tank T1, which is a fuel tank for supply, as described above, and the second fuel tank for replacement, as described above, is supplied with LNG. When performing the replacement process of the fuel tank T2, the isolation valve IV communicates with the liquid crossover line LC and the liquid line LL to the side where the first liquid line LL1 is branched, and the second It is controlled so that the liquid line LL2 does not communicate with the liquid line LL on the branched side.

However, under the control of the isolation valve IV, the liquid crossover line LC and the liquid line LL communicate only with the supply fuel tank, that is, the first fuel tank T1 side, and the replacement fuel tank, that is, It does not communicate with the second fuel tank T2 side.

In this way, when supplying LNG to the first fuel tank T1 and performing the replacement process of the second fuel tank T2 at the same time, supplying LNG to the first fuel tank T1 and the second fuel tank T2 All of the inert gas discharge from the liquid line LL is performed, but the isolation valve IV allows LNG to flow from the manifold L to the first fuel tank T1 based on the isolation valve IV. The path and the path through which the inert gas flows from the second fuel tank T2 to the vent mast VM are blocked to isolate each other.

As described above, the embodiments according to the present invention have been reviewed, and the fact that the present invention can be embodied in other specific forms without departing from the spirit or scope of the present invention in addition to the above-described embodiments is recognized by those with ordinary skill in the art. It is self-evident to Therefore, the above-described embodiments are to be regarded as 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.

T1, T2, T3, T4: LNG fuel tank
LL, LL1, LL2, LL3, LL4: Liquid line
SL, SL1, SL2, SL3, SL4: stripping line
GL, GL1, GL2, GL3, GL4: gas line
CL : connecting line
LC: Liquid Crossover Line
IV: isolation valve
VM: Vent Mast
100: compressor
200: heater

Claims (5)

A system for supplying liquefied gas fuel from a liquefied gas supply ship to a liquefied gas fuel ship including two or more liquefied gas fuel tanks,
A first fuel tank for storing liquefied gas fuel; and
Includes; a second fuel tank for storing liquefied gas fuel;
From the liquefied gas supply vessel, liquefied gas fuel is supplied using a liquid branch line or a stripping branch line connected to the first fuel tank, and at the same time, the boil-off gas discharged from the first fuel tank is replaced by the second fuel tank A ship's liquefied gas fuel supply system that supplies gas for use. The method according to claim 1,
Further comprising a gas line through which the boil-off gas is transferred,
In the gas line,
a compressor for compressing the boil-off gas; and
A heater for heating the boil-off gas compressed by the compressor; is provided,
A liquefied gas fuel supply system for a ship that compresses and heats the boil-off gas transferred from the first fuel tank to the second fuel tank and supplies it. The method according to claim 1,
a liquid line 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 is branched from the liquid line and a point where the liquid branch line of the second fuel tank branches from the liquid line; gas fuel supply system. 4. The method according to claim 3,
When liquefied gas is supplied to the first fuel tank using the liquid branch line, the gas discharged from the second fuel tank is discharged through the liquid branch line connected to the second fuel tank, and the isolation valve is closed , liquefied gas fuel supply systems for ships. 5. The method according to claim 4,
A connecting line connecting the liquid line and the vent mast; further comprising,
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 vent mast through the liquid line and the connect line, the liquefied gas fuel supply system of the ship .

Images