Fuel gas supply system of ship

Abstract

A fuel gas supply system for a ship is disclosed. The fuel gas supply system for a ship according to the present invention comprises: a main engine capable of operating using fuel gas and equipped as a propulsion engine for the ship; a fuel tank in which fuel gas is stored; a fuel supply unit that supplies the fuel gas stored in the fuel tank according to conditions required by the main engine; a Gas Valve Train (GVT) that finally controls the pressure and flow rate of the fuel gas compressed in the fuel supply unit and supplies it to the main engine; and a high-pressure fuel gas supply line connected from the GVT to the main engine and provided as a double pipe, wherein the high-pressure fuel gas supply line is characterized in that the outer pipe is formed under vacuum so that the outer pipe can be rapidly replaced with nitrogen gas in the event of a leak in the inner pipe.

Description

Technology Field

[0001] The present invention relates to a fuel gas supply system for a ship, and more specifically, to a fuel gas supply system for a ship that can be suitably applied to an LFS operated with a separate fuel tank. Background Technology

[0002] Generally, combustion devices such as engines installed on various vessels have used oils like MDO (Marine Diesel Oil) and HFO (Heavy Fuel Oil) as fuel. However, these fuel oils have been a major culprit in causing environmental pollution due to greenhouse gases and various harmful substances generated during combustion. Furthermore, when oil prices rise due to factors such as the depletion of fossil fuels or instability in the international situation, operational problems arise, such as skyrocketing fuel costs.

[0003] Recently, as air pollution regulations have become increasingly stricter, clean fuels such as liquefied natural gas (LNG), which has low levels of sulfur oxides (SOx) and nitrogen oxides (NOx), are gaining attention as alternative energy sources to fuel oil, and dual fuel engines (DF engines) capable of using both fuel oil and fuel gas have been developed and are being used in ships.

[0004] Meanwhile, technology utilizing LNG stored in tanks as engine fuel has already been applied to LNG carriers (LNG Carriers) that transport large quantities of LNG; recently, there is a trend of gradually expanding the use of LNG fuel to vessels other than LNG Carriers, and its application is being considered, particularly for Very Large Crude-Oil Carriers (VLCCs) and container ships.

[0005] Unlike LNGCs, which carry LNG directly as cargo and use it as fuel, general vessels must have a separate LNG fuel tank to use LNG as fuel. Vessels operated with such a separate LNG fuel tank are called LFS (LNG Fueled Ship).

[0006] However, unlike conventional LNGCs, LFS has a complex fuel supply system, requiring technology to address this. The problem to be solved

[0007] Accordingly, the present invention aims to provide a fuel gas supply system for a ship that can be suitably applied to an LFS, and in particular, to configure a system that can ensure stability while satisfying classification society requirements and reduce power consumption. means of solving the problem

[0008] According to one aspect of the present invention for achieving the above-mentioned purpose, a fuel gas supply system for a ship may be provided, comprising: a main engine capable of operating using fuel gas and equipped as a propulsion engine for a ship; a fuel tank in which the fuel gas is stored; a fuel supply unit that supplies the fuel gas stored in the fuel tank according to conditions required by the main engine; a Gas Valve Train (GVT) that finally controls the pressure and flow rate of the fuel gas compressed in the fuel supply unit and supplies it to the main engine; and a high-pressure fuel gas supply line connected from the GVT to the main engine and provided as a double pipe, wherein the high-pressure fuel gas supply line is characterized in that the outer pipe is formed under vacuum so that the outer pipe can be rapidly replaced with nitrogen gas in the event of a leak in the inner pipe.

[0009] The fuel gas supply system of a ship according to the present invention may further include an ejector that draws in gas present in the outer tube to form a vacuum; and a nitrogen supply unit that supplies compressed nitrogen gas as a driving fluid for the ejector.

[0010] In addition, the fuel gas supply system of a ship according to the present invention may further include: a vacuum suction line for sucking gas inside the outer tube toward the ejector; a vacuum discharge line for discharging the gas sucked into the ejector through the vacuum suction line overboard; and a nitrogen supply line for supplying the compressed nitrogen gas from the nitrogen supply unit to the ejector.

[0011] In addition, the fuel gas supply system of a ship according to the present invention may further include a three-way valve installed on the vacuum injection line; and a nitrogen filling line branched from the vacuum injection line at the point where the three-way valve is installed and connected to the outer pipe, and when a leak occurs in the inner pipe, the three-way valve may be switched toward the nitrogen filling line to fill the outer pipe with nitrogen gas supplied from the nitrogen supply unit to the ejector.

[0012] The vacuum suction line and the nitrogen filling line are each connected to the ends of the high-pressure fuel gas supply line, and the connection points of the vacuum suction line and the nitrogen filling line are formed as far apart as possible, thereby enabling smooth circulation of the outer pipe.

[0013] The above nitrogen supply unit can supply nitrogen gas as a purging gas for purging the main engine.

[0014] The fuel gas supply system of a ship according to the present invention may further include a purging line that supplies nitrogen gas from the nitrogen supply unit for the purpose of purging the main engine, and the nitrogen gas supplied to the purging line may be supplied to the main engine to purge the interior of the main engine and the high-pressure fuel gas supply line, and then discharged to the outside air through the GVT.

[0015] The fuel supply unit and the GVT are positioned within a cargo compressor room, and the cargo compressor room may be located in the cargo area of ​​the vessel.

[0016] The above cargo compressor room may be classified as a gas hazardous zone where periodic ventilation is performed.

[0017] The above cargo area may be located in front of the engine room in the stern where the main engine is positioned.

[0018] The fuel gas supply system of a ship according to the present invention may further include a cofferdam partitioned at the boundary between the engine room and the cargo area, and the high-pressure fuel gas supply line may pass through the interior of the cofferdam, penetrate the front bulkhead of the engine room, and be connected to the main engine.

[0019] The above cofferdam can perform periodic ventilation of its internal space.

[0020] The fuel gas supply system of a ship according to the present invention may further include an exhaust fan installed on a first vent line for discharging air inside the cofferdam; and an eductor installed on a second vent line for discharging air inside the cofferdam, and ventilation inside the cofferdam may be achieved by selectively operating the exhaust fan and the eductor individually or simultaneously.

[0021] When the above-mentioned inductor is operated individually, the inductor can be operated by receiving pressure from the compressed nitrogen gas supplied from the nitrogen supply unit.

[0022] In cases where ventilation inside the cofferdam is performed using only the above-mentioned inductor, it may be possible to eliminate the exhaust fan.

[0023] When the exhaust fan and the inductor are operated simultaneously, the inductor can be operated by receiving at least one of the pressure formed by the exhaust fan and the pressure from the compressed nitrogen gas supplied from the nitrogen supply unit. Effects of the invention

[0024] The fuel gas supply system for a ship according to the present invention uses a pressurized fuel tank and configures the line supplying fuel gas to the engine as a vacuum double pipe, thereby satisfying classification society requirements while significantly improving the stability of the system.

[0025] In addition, according to the present invention, when a leak occurs in a fuel supply line and a fuel gas supply line composed of double pipes, it is possible to quickly discharge the leaked gas, which is an operational advantage in that it is possible to quickly restart the engine in an emergency, and it is also possible to discharge the leaked gas to a desired area using pressure, which is an advantage in piping design.

[0026] In addition, according to the present invention, it is possible to reduce the power consumption of the exhaust fan provided in the gas valve unit room, and in some cases, it is also possible to remove the exhaust fan, thereby having the effect of reducing OPEX and CAPEX. Brief explanation of the drawing

[0027] FIG. 1 is a schematic diagram showing a fuel gas supply system for a ship according to the present invention. Specific details for implementing the invention

[0028] In order to fully understand the present invention, the operational advantages of the present invention, and the objectives achieved by the implementation of the present invention, reference must be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

[0029] In this specification, "fuel gas" used as fuel for ships may include all types of liquefied gases that can be stored by liquefying at low temperatures and supplied as fuel to engines in a vaporized state, such as LNG, LPG (Liquefied Petroleum Gas), LEG (Liquefied Ethane Gas), Liquefied Ethylene Gas, and Liquefied Propylene Gas. However, for the sake of convenience of explanation, LNG, a representative liquefied gas, will be used as an example for the following description.

[0030] In addition, the term "ship" in this specification may be interpreted as a concept that includes all types of vessels capable of using fuel gas as fuel for an engine. Representative examples include vessels with self-propulsion capabilities, such as LFS that use LNG as fuel, as well as offshore structures floating on the sea, such as LNG FPSO (Floating Production Storage Offloading) or LNG FSRU (Floating Storage Regasification Unit).

[0031] The present invention will be described in detail below by explaining preferred embodiments of the invention with reference to the attached drawings. Identical reference numerals in each drawing indicate identical components.

[0033] FIG. 1 is a schematic diagram showing a fuel gas supply system for a ship according to the present invention.

[0034] Referring to FIG. 1, the fuel gas supply system according to the present invention may include: a gas engine (110) and a main engine (120) that use LNG as fuel; a fuel tank (200) that stores LNG supplied as fuel to the engine (110, 120); a fuel supply unit (300) that supplies LNG stored in the fuel tank (200) according to the conditions required by the engine (110, 120); and a nitrogen supply unit (400) that supplies nitrogen gas for the purpose of pressurizing the fuel tank (200) to control internal pressure and for the purpose of purging the inside of the engine (110, 120) and the line through which LNG is supplied to the engine (110, 120).

[0036] The engine (110, 120) may be an engine capable of being driven using LNG as fuel. Therefore, it includes a Dual Fuel Engine (DF) capable of using both heavy oil and natural gas as fuel, and can be applied to propulsion engines such as ME-GI engines or X-DF (eXtreme Dual Fuel) engines, or general generator engines such as DFDG (Dual Fuel Diesel Generator).

[0037] In a preferred embodiment of the present invention, the gas engine (110) may be a low-pressure gas injection engine driven by receiving fuel gas of approximately 10 bar or less, and may be a generator engine that produces power required on board, and the main engine (120) may be a high-pressure gas injection engine driven by receiving fuel gas of approximately 200 to 400 bar, and may be a propulsion engine for the ship, for example, equipped as an ME-GI engine.

[0038] The engines (110, 120) are placed in the engine room (E / R) located at the stern. The engine room (E / R) is classified as a gas safe zone and is a zone where safety from the gas hazardous zone must be ensured. For example, direct access from the gas hazardous zone to the gas safe zone is prohibited (installation of an air lock if necessary), and fuel supply pipes passing through the gas safe zone must be completely enclosed by a double pipe or duct.

[0040] The fuel tank (200) can be provided as a pressurized (pressure-type) tank that stores LNG supplied as fuel for the engine (100) in a liquefied state and maintains a constant pressure above a certain level.

[0041] The fuel tank (200) may include a pressurizing unit (210) that is pressurized by nitrogen gas supplied from a nitrogen supply unit (400) through a pressure maintaining line (ML) in order to maintain internal pressure.

[0042] The pressurizing unit (210) forms part of the fuel tank (200) and can control the pressure of the fuel tank (200) by transmitting pressure energy from nitrogen gas supplied from the nitrogen supply unit (400) to the fuel tank (200).

[0043] For example, the fuel tank (200) and the pressurizing unit (210) may be manufactured as a single tank, and the space may be partitioned by a diaphragm capable of contracting and expanding or reciprocating by a piston, so that the pressure of the fuel tank (200) can be controlled by adjusting the amount of nitrogen gas supplied to the internal space of the pressurizing unit (210).

[0044] A tank pressure sensor (201) for measuring the internal pressure of the tank may be installed in the fuel tank (200). When the value measured by the tank pressure sensor (201) drops below a certain level, nitrogen gas is supplied from the nitrogen supply unit (400) to the pressurizing unit (210) to ensure that the fuel tank (200) maintains a pressure above a certain level and prevents the LNG inside the fuel tank (200) from vaporizing.

[0045] The fuel tank (200) may be positioned on the upper part of the main deck at the stern so as to be close to the engine (110, 120), but the present invention is not limited thereto. Recently, there has been a trend in container ships to place accommodations in the central part of the ship to ensure visibility. When the present invention is applied to such a container ship, the fuel tank (200) may be placed in the lower space of the accommodation where it is difficult to load containers. In this case, the accommodation and the fuel tank (200) may be separated by a cofferdam, etc.

[0046] In addition, the fuel tank (200) of the present invention may be provided as an independent type tank that can be mounted, and may be a pressurized tank, but it is also obvious that it may be provided as a membrane type tank made using the inner wall of the hull.

[0048] The fuel supply unit (300) is configured to supply LNG stored in the fuel tank (200) according to the conditions required by the engine (110, 120), and can supply the LNG stored in the fuel tank (200) to the engine (110, 120) by forcibly vaporizing and compressing it, or can supply the BOG (evaporated gas) generated by the natural vaporization of LNG in the fuel tank (200) to the engine (110, 120) by compressing it.

[0049] The fuel supply unit (300) may include a vaporizer for forcibly vaporizing LNG, a compressor for compressing LNG vaporized by the vaporizer or naturally occurring BOG in the fuel tank (200) to a pressure required by the engine (110, 120), a heater, etc.

[0050] Meanwhile, since the pressure and temperature of the fuel gas required by the gas engine (110) driven by receiving low-pressure gas and the main engine (120) driven by receiving relatively high-pressure fuel gas are different, it is necessary to supply fuel gas that meets the conditions required by each engine (110, 120). To this end, in order to meet the conditions of the main engine (120) that requires high-pressure fuel gas, the compressor may be configured as a multi-stage compressor, and a known method may be used, such as supplying fuel gas that has passed through only a part of the multi-stage compressor to the gas engine (110) that requires relatively low-pressure fuel gas.

[0051] In addition, since the pressure of the fuel gas required by the gas engine (110) and the main engine (120) is different, fuel gas supply lines (SL1, SL2) connecting from the fuel supply unit (300) to the gas engine (110) and the main engine (120) may each be provided.

[0052] At this time, a valve device is installed on the fuel gas supply line (SL1, SL2) to rapidly control the pressure of the fuel gas supplied to the engine (110, 120) according to the load of the engine (110, 120) and to rapidly cut off the supply of fuel gas when necessary.

[0053] In the present invention, control valves installed on a first fuel gas supply line (SL1) connected to a gas engine (110) are grouped and referred to as a Gas Valve Unit (hereinafter GVU) (310), and control valves installed on a second fuel gas supply line (SL2) connected to a main engine (120) are grouped and referred to as a Gas Valve Train (hereinafter GVT) (320).

[0054] The fuel supply unit (300) and the GVT (320) may be placed within the Cargo Compressor Room (10), and the Cargo Compressor Room (10) may be placed in the Cargo Area. Here, the Cargo Area may refer to the area generally referred to as the Cargo Area in a ship, and in this embodiment, it may refer to a safe area located in front of the Engine Room Area (E / R Area) as a space where cargo is loaded. Additionally, in the case of an LNGC, the upper part of the Cargo Tank may be defined as the Cargo Area, and in this case, the Cargo Area may refer to an area where LNG gas may be exposed.

[0055] In the present invention, the cargo compressor room (10) may be placed in a separate space on the upper part of the main deck on the stern side of the cargo area so as to be close to the engine (110, 120). However, the present invention is not limited thereto, and as described above, when the present invention is applied to a container ship, the cargo compressor room (10) may be placed together with the fuel tank (200) in the lower part of the accommodation area.

[0056] Unlike the GVT (320) which is placed in the cargo compressor room (10), the GVU (310) may be placed in the gas valve unit room (GVU Room, hereinafter GVU Room) (20) located at the rear of the engine room (E / R). This is because, unlike the GVT (320) which handles high-pressure fuel gas, the GVU (310) handles relatively low-pressure fuel gas and therefore must be placed close to the gas engine (110).

[0057] The GVU room (20) is a space classified as a gas hazard zone and must be located in an isolated area separate from the engine room (E / R). Additionally, periodic ventilation must be performed for safety reasons, and dry air is typically exchanged 30 times per hour to prevent gas leakage. Therefore, the GVU room (20) may be equipped with an exhaust fan (F2) to enable ventilation at any time. The exhaust fan (F2) must be operated at all times in the gas mode when the gas engine (110) uses LNG as fuel.

[0059] In the present invention, the process of supplying fuel gas from the fuel tank (200) to the engine (110, 120) can be carried out as follows. First, LNG stored in the fuel tank (200) is supplied to the fuel supply unit (300) through the fuel supply line (FL). The (low-pressure) fuel gas supplied from the fuel supply unit (300) to the gas engine (110) is supplied to the gas engine (110) through the first fuel gas supply line (SL1), and in this process, the pressure and flow rate are finally controlled at the GVU (310). The (high-pressure) fuel gas supplied from the fuel supply unit (300) to the main engine (120) is supplied to the main engine (120) through the second fuel gas supply line (SL2) after the pressure and flow rate are controlled by the GVT (320) within the cargo compressor room (10).

[0060] Here, the fuel supply line (FL) can be provided as a double pipe. This is a design to satisfy classification society requirements, and the fuel supply line (FL) is configured as a double pipe because the fuel tank (200) has pressure.

[0061] Meanwhile, among the first fuel gas supply lines (SL1), the line (SL1-1) placed on the weather deck and inside the GVU room (20) can be configured as a single pipe. This is because the first fuel gas supply line (SL1) handles low-pressure fuel gas of approximately 10 bar or less, and the GVU room (20) is a gas hazard zone configured to allow ventilation at all times.

[0062] On the other hand, the line (SL1-2) connecting from the GVU (310) to the gas engine (110) among the first fuel gas supply lines (SL1) must be provided as a double pipe since it is placed within the engine room (E / R) classified as a gas safety zone.

[0063] In addition, the second fuel gas supply line (SL2) must be composed entirely of double pipes from the rear end of the GVT (320) to the main engine (120) to handle high-pressure fuel gas of approximately 200 to 400 bar.

[0064] In the present invention, the second fuel gas supply line (SL2) may be arranged to pass through the interior of a coffer dam (30) partitioned at the boundary between the engine room (E / R) and the cargo area, and may be extended downward as much as possible to the location of the main engine (120), and then penetrate the front bulkhead of the engine room (E / R) to be connected to the main engine (120).

[0065] The present invention can be configured to allow periodic ventilation (air exchange 30 times per hour) to be performed even in the internal space of the coffer dam (30), and for this purpose, an exhaust fan (F1) can also be provided in the coffer dam (30).

[0066] At this time, the present invention may perform ventilation inside the cofferdam (30) by installing a first eductor (610) as a backup for the exhaust fan (F1). That is, ventilation inside the cofferdam (30) may be performed by the exhaust fan (F1) or the first eductor (610), or the exhaust fan (F1) and the first eductor (610) may be operated together to enable ventilation to be performed more quickly.

[0067] Typically, ventilation using an exhaust fan (F1) has the disadvantage of high power consumption. However, the present invention has the effect of increasing ventilation efficiency and reducing the power consumption of the exhaust fan (F1) by installing a first eductor (610) to replace the role of the exhaust fan (F1) or to assist the role of the exhaust fan (F1). In addition, rapid response is possible even when ventilation needs to be performed urgently.

[0068] Specifically, when the first eductor (610) is operated individually, the first eductor (610) can perform ventilation inside the cofferdam (30) by receiving compressed nitrogen gas provided from the nitrogen supply unit (400) as a driving fluid.

[0069] To this end, a first pressure supply line (OL1) that supplies nitrogen gas from a nitrogen supply unit (400) to the first pressure supply line (610) may be connected to the first pressure supply line (OL1), and a first pressure control valve (OV1) that controls the supply of nitrogen gas may be installed on the first pressure supply line (OL1).

[0070] When the exhaust fan (F1) and the first eductor (610) are operated together, the first eductor (610) may be operated by receiving positive pressure provided by the exhaust fan (F1), or simultaneously receive additional nitrogen gas provided from the aforementioned nitrogen supply unit (400) as a driving fluid.

[0071] As illustrated in FIG. 1, the first eductor (610) may be installed to be connected to the rear end of the exhaust fan (F1), and a first vent line (VL1) for discharging air through the exhaust fan (F1) and a second vent line (VL2) for discharging air through the first eductor (610) may each be provided in consideration of the individual operation of the first eductor (610) and the exhaust fan (F1).

[0072] Additionally, a first backflow prevention valve (BV1) may be installed on the line connecting the first eductor (610) and the exhaust fan (F1). The first backflow prevention valve (BV1) serves to isolate the first eductor (610) and the exhaust fan (F1) when they are operated individually, and when they are operated simultaneously, it prevents pressure loss from the first eductor (610) to the exhaust fan (F1), thereby increasing the efficiency of the first eductor (610).

[0074] As described above, the present invention configures the fuel supply line (FL), a part of the first fuel gas supply line (SL1), and the second fuel gas supply line (SL2) into a double-pipe structure, thereby ensuring double safety by the outer pipe surrounding the inner pipe even if LNG gas leaks from the inner pipe.

[0075] A gas sensor (GD) can be installed in each of the fuel supply line (FL), the line (SL1-2) composed of a double pipe in the first fuel gas supply line (SL1), and the second fuel gas supply line (SL2) to detect leakage in the inner pipe.

[0076] In addition, the present invention is characterized by configuring the system such that the outer tubes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2), which are composed of double tubes, are formed into a vacuum state so that the outer tubes can be rapidly replaced with nitrogen gas in the event of LNG gas leakage from the inner tubes.

[0077] The fuel gas supply system of a ship according to the present invention may further include an ejector (500) installed to form a vacuum state in the outer tubes of a fuel supply line (FL) composed of a double pipe, a first fuel gas supply line (SL1-2), and a second fuel gas supply line (SL2).

[0078] The ejector (500) draws in gas between the outer tube and the inner tube of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2) to form a vacuum.

[0079] Specifically, the outer pipe of the fuel supply line (FL) is connected to the ejector (500) through the first vacuum suction line (IL1), the first fuel gas supply line (SL1-2) is connected to the ejector (500) through the second vacuum suction line (IL2), and the second fuel gas supply line (SL2) can be connected to the ejector through the third vacuum suction line (IL3). At this time, the first vacuum suction line (IL1), the second vacuum suction line (IL2), and the third vacuum suction line (IL3) can be integrated into a single line and connected to the suction port of the ejector (500).

[0080] Air present in the outer tubes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2) is sucked into the ejector (500) and discharged to the outside (outside the ship) through the vacuum injection line (EL), and accordingly, the outer tubes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2) can be formed into a vacuum state.

[0081] At this time, nitrogen gas supplied from the nitrogen supply unit (400) may be used as the driving fluid of the ejector (500). The nitrogen supply unit (400) supplies compressed nitrogen gas as the driving fluid of the ejector (500) through the nitrogen supply line (NL) to provide pressure that sucks in air present in the outer tubes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2).

[0082] Pressure sensors (PT) may be installed on the outer pipes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2) for the purpose of measuring the vacuum level. In this case, the pressure sensors (PT) installed on the first fuel gas supply line (SL1-2) and the second fuel gas supply line (SL2) entering the engine room (E / R) can be configured to be located within the engine room (E / R) so that explosion-proof design is not required, thereby allowing for expected cost reduction.

[0083] A first vacuum control valve (IV1), a second vacuum control valve (IV2), and a third vacuum control valve (IV3) may be installed on the first vacuum suction line (IL1), the second vacuum suction line (IL2), and the third vacuum suction line (IL3), respectively. The first vacuum control valve (IV1), the second vacuum control valve (IV2), and the third vacuum control valve (IV3) may be shut off when the vacuum in the outer pipes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2) is perfectly formed.

[0084] Additionally, a nitrogen control valve (NV) that controls the supply of nitrogen gas from the nitrogen supply unit (400) to the ejector (500) may be installed on the nitrogen supply line (NL). When the first to third vacuum control valves (IV1, IV2, IV3) are shut off as vacuum formation is completed, the nitrogen control valve (NV) is also shut off to stop the consumption of nitrogen gas, thereby saving energy.

[0085] A three-way valve (3V) may be installed on the vacuum injection line (IL4). When a vacuum is formed in the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2), the three-way valve (3V) is opened to discharge the fluid sucked into the ejector (500) to the outside (outside the ship).

[0086] Meanwhile, the present invention may further include nitrogen filling lines (CL1, CL2, CL3) for filling nitrogen gas discharged into a vacuum injection line (EL) into the outer pipes of a fuel supply line (FL), a first fuel gas supply line (SL1-2), and a second fuel gas supply line (SL2).

[0087] The nitrogen filling lines (CL1, CL2, CL3) branch off from the point where the three-way valve (3V) is installed on the vacuum injection line (EL) and are connected to the outer pipes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2), respectively.

[0088] In the event that a leak occurs in one or more of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2), the nitrogen gas supplied to the ejector (500) by the nitrogen supply unit (400) is not discharged to the outside (outside the ship) through the vacuum injection line (EL), but is supplied to the outer pipe of the leaking line through the nitrogen filling lines (CL1, CL2, CL3).

[0089] At this time, since a vacuum is formed in the outer pipes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2), they can be rapidly replaced with nitrogen gas in a vacuum state. Additionally, the ejector (500) can play a role in helping the outer pipe of the leaking line to be replaced with nitrogen gas even more rapidly.

[0090] A first nitrogen filling valve (CV1), a second nitrogen filling valve (CV2), and a third nitrogen filling valve (CV3) may be installed on the first nitrogen filling line (CL1), the second nitrogen filling line (CL2), and the third nitrogen filling line (CL3), respectively. The first to third nitrogen filling valves (CV1, CV2, CV3) are normally closed so that the outer pipes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2) can be kept in a vacuum state, and are opened only when the outer pipes are replaced with nitrogen gas.

[0091] In the event that a leak occurs in the inner pipe of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2), the operation of replacing the outer pipe with nitrogen gas can be performed as follows.

[0092] First, the vacuum control valves (IV1, IV2, IV3) on the line side where the leak occurred are opened, and compressed nitrogen gas is supplied from the nitrogen supply unit (400) to the nitrogen supply line (NL) to operate the ejector (500). Accordingly, the leaked gas is sucked into the ejector (500) through the vacuum suction lines (IL1, IL2, IL3) and then discharged to the outside (outside the ship) through the vacuum injection line (EL).

[0093] When it is determined that the discharge of the leaked gas is complete, the nitrogen filling valves (CV1, CV2, CV3) on the leaking line side are opened, and nitrogen gas is filled into the outer pipe of the leaking line at a pressure above a certain level.

[0094] Afterwards, the three-way valve (3V) is switched toward the nitrogen filling line (CL1, CL2, CL3) on the side of the leaking line to rapidly replace the outer pipe of the leaking line with nitrogen gas. At this time, the three-way valve (3V) opens as much as is required to remove all the gas inside the outer pipe of the leaking line, and then switches direction toward the nitrogen filling line (CL1, CL2, CL3).

[0095] Once the process of replacing the outer pipe of the leaking line with nitrogen gas is completed, the vacuum control valves (IV1, IV2, IV3) and nitrogen filling valves (CV1, CV2, CV3) are shut off. That the replacement work on the corresponding line has been completed can be confirmed through the pressure sensors (PT) installed on each line.

[0096] Meanwhile, it is desirable to induce smooth circulation by ensuring that the first vacuum suction line (IL1) and the nitrogen filling line (CL1), which are connected to the fuel supply line (FL), are connected to the ends of the fuel supply line (FL), that is, so that the connection points of the first vacuum suction line (IL1) and the nitrogen filling line (CL1) are located as far apart as possible. This concept can be applied in the same way to the first fuel gas supply line (SL1-2) or the second fuel gas supply line (SL2).

[0098] As described above, if an LNG gas leak occurs, the engine (110, 120) connected to the leaked line can no longer operate in gas mode. In this case, the supply of LNG gas by the fuel supply unit (300) must be stopped and the engine (110, 120) must be purged.

[0099] In the present invention, the purging operation of the engine (110, 120) can be carried out by nitrogen gas supplied from the nitrogen supply unit (400) through the purging lines (PL1, PL2).

[0100] Specifically, the nitrogen supply unit (400) is connected to the gas engine (110) and the main engine (120), respectively, through the first purging line (PL1) and the second purging line (PL2), and directly supplies nitrogen gas to the engines (110, 120) when it is necessary to purge the engines (110, 120). A first purging valve (PV1) and a second purging valve (PV2) that control the supply of nitrogen gas from the nitrogen supply unit (400) to the engines (110, 120) may be installed on the first purging line (PL1) and the second purging line (PL2).

[0101] Nitrogen gas supplied to the engine (110, 120) through the purging lines (PL1, PL2) pushes out residual gas inside the engine (110, 120), and residual gas discharged from the engine (110, 120) pushed out by the nitrogen gas can be discharged to a safe area (e.g., outside air) through the GVU (310) or GVT (320).

[0102] Specifically, when purging the gas engine (110), the residual gas discharged from the gas engine (110) is discharged in the opposite direction to the direction in which the fuel gas is supplied through the first fuel gas supply line (SL1-2) and can be discharged into a safe area through the third vent line (VL3) connected to the GVU (310). A vent valve (VV3) for opening and closing the line may be installed on the third vent line (VL3).

[0103] Similarly, when purging the main engine (120), the residual gas discharged from the main engine (120) is discharged in the opposite direction to the direction in which the fuel gas is supplied through the second fuel gas supply line (SL2) and can be discharged into a safe zone through the GVT (320).

[0104] Conventionally, to purge the interior of an engine using LNG fuel, a purging gas (e.g., nitrogen gas) was supplied to the piping side where LNG gas is supplied, and the residual gas emitted from the engine was discharged through a vent mast via the exhaust line through which exhaust gas is discharged.

[0105] Therefore, conventionally, engine purging was performed in the direction of the fuel gas supply line → engine → safe area. According to this conventional technology, the exhaust line that discharges residual gas from the engine is placed inside the engine room, which increases the risk, and the gas piping passing through the engine room, which is classified as a gas safety zone, must be constructed as a double pipe or enclosed by a duct, which is disadvantageous in terms of cost.

[0106] However, in the present invention, by directly supplying nitrogen gas from the nitrogen supply unit (400) to the engine (110, 120), it can be seen that the purging of the engine is performed in the direction of engine (110, 120) → GVU (310) or GVT (320) → Safe Area. That is, the purging of the engine (110, 120) is performed in the opposite direction to the conventional method.

[0107] According to the present invention, residual gas discharged from the engine (100) can be discharged using the first fuel gas supply line (SL1-2) or the second fuel gas supply line, which is 'already configured as a double pipe,' thereby increasing the utilization of existing equipment and eliminating the need for a separate gas pipe to discharge residual gas inside the engine room (E / R), thus enabling cost reduction due to reduced volume.

[0108] In addition, the gas piping placed inside the engine room (E / R), where electrical equipment, oil handling equipment, and ignition equipment are placed, can be significantly reduced, thereby maximizing safety. Furthermore, since the cargo compressor room (10) and GVU room (20), which are classified as gas hazard zones, always have 30 air exchanges per hour, using these zones to discharge residual gas from the engine (110, 120) is very advantageous for ventilation.

[0109] Of course, the purging operation of the engine (110, 120) described above can be applied not only when an LNG gas leak occurs, but also when the engine (110, 120) is to be stopped for a long time or when internal systems are to be maintained, or when the fuel used by the engine (110, 120) is to be changed from LNG to fuel oil.

[0111] Meanwhile, the present invention allows the second eductor (620) to be installed on the third vent line (VL3) extending from the GVU (310) so that the purging operation of the gas engine (110) can be performed more quickly.

[0112] The installation and operation of the second eductor (620) can be applied almost identically to the technical concept described in the first eductor (610) mentioned above.

[0113] Specifically, the second inductor (620) may be installed to be connected to the rear end of the exhaust fan (F2), and a second backflow prevention valve (BV) may be installed on the line connecting the second inductor (620) and the exhaust fan (F2) to separate the second inductor (620) and the exhaust fan (F2) or to prevent pressure loss from the second inductor (620) to the exhaust fan (F2).

[0114] A second pressure supply line (OL2) that supplies nitrogen gas from the nitrogen supply unit (400) to the second pressure supply line (620) may be connected to the second pressure supply line (OL2), and a second pressure control valve (OV2) that controls the supply of nitrogen gas may be installed on the second pressure supply line (OL2).

[0115] The second eductor (620) can be operated individually or simultaneously with the exhaust fan (F2). When operated individually, it receives compressed nitrogen gas supplied from the nitrogen supply unit (400) as the driving fluid. When operated together with the exhaust fan (F2), it is operated by receiving positive pressure formed by the exhaust fan (F2) or simultaneously receives additional nitrogen gas supplied from the nitrogen supply unit (400) as the driving fluid, as explained in the first eductor (610) described above.

[0116] In this way, the present invention has the effect of increasing the efficiency of ventilation and reducing the power consumption of the exhaust fan (F2) by installing a second eductor (620) when performing ventilation of the GVU room (20). In particular, when the second eductor (620) is operated using the pressure of nitrogen gas supplied from the nitrogen supply unit (400), the power consumption of the exhaust fan (F2) can be significantly reduced compared to the conventional method, thereby reducing OPEX, or it is possible to remove the exhaust fan (F2) altogether, thereby reducing CAPEX.

[0117] In addition, the present invention makes it possible to discharge residual gas inside the gas engine (110) to a desired area using the pressure formed in the second eductor (620). According to the existing design, there were constraints that the vent pipe of the gas piping had to be positioned high and a large pipe had to be used considering the pressure drop. However, when applying the present invention, it is possible to discharge residual gas to a desired area using the pressure formed in the second eductor (620), so the third vent line (VL3) can be placed at any location that is safe, which provides an advantage in piping design and is expected to have a cost-saving effect.

[0119] As seen above, the nitrogen supply unit (400) in the present invention can have the following five roles.

[0120] 1) The role of supplying nitrogen gas to the pressurizing unit (210) to control the internal pressure of the fuel tank (100).

[0121] 2) The role of supplying nitrogen gas as the driving fluid of the ejector (500) to form a vacuum state in the outer tubes of the fuel supply line (FL), the first fuel gas supply line (SL1-2), and the second fuel gas supply line (SL2).

[0122] 3) A role of supplying nitrogen gas to fill the outer pipe in case of leakage in the fuel supply line (FL), the first fuel gas supply line (SL1-2) and the second fuel gas supply line (SL2).

[0123] 4) Role of supplying nitrogen gas as a purging gas for the engine (110, 120).

[0124] 5) A role of supplying nitrogen gas to provide pressure to an inductor (610, 620) installed for ventilation of a cofferdam (30) or GVU room (20).

[0125] For the above roles, the nitrogen supply unit (400) of the present invention may include a nitrogen generator (N2 Generator) that generates nitrogen, a nitrogen buffer tank (N2 Buffer Tank) that temporarily stores the nitrogen generated by the nitrogen generator and regulates the supply, a nitrogen compressor (N2 Compressor) that compresses nitrogen gas, etc., and may be placed inside the engine room (E / R).

[0126] In addition, although the present invention uses nitrogen gas, a representative inert gas, as an example to construct a safe system, it is of course possible to use other inert gases with minimal chemical reactions in addition to nitrogen gas.

[0128] It is obvious to those skilled in the art that the present invention is not limited to the described embodiments and can be modified and varied in various ways without departing from the spirit and scope of the invention. Accordingly, such modifications or variations should be deemed to fall within the scope of the claims of the present invention. Explanation of the symbols

[0129] 110: Gas engine 120: Main engine 200: Fuel tank 210: Pressurizing part 300: Fuel supply unit 310: GVU 320: GVT 400: Nitrogen supply unit 500: Ejector 610: 1st Iductor 620: Second Iductor ML: Pressure maintenance line FL: Fuel supply line SL1: 1st Fuel Gas Supply Line SL2: Second fuel gas supply line NL: Nitrogen supply line IL1: 1st vacuum suction line IL2: Second vacuum suction line IL3: 3rd vacuum suction line EL: Vacuum injection molding line 3V: Three-way valve CL1: 1st Nitrogen Filling Line CL2: 2nd nitrogen filling line CL3: 3rd nitrogen filling line PL1: 1st Purge Line PL2: 2nd Purge Line OL1: 1st pressure supply line OL2: Second pressure supply line OV1: First pressure control valve OV2: Second pressure control valve VL1: 1st vent line VL2: 2nd vent line VL3: 3rd ventline

Claims

Claim 1 A main engine capable of operating using fuel gas and equipped as a propulsion engine for a ship; a fuel tank in which the fuel gas is stored; a fuel supply unit that supplies the fuel gas stored in the fuel tank according to the conditions required by the main engine; a Gas Valve Train (GVT) that finally controls the pressure and flow rate of the fuel gas compressed in the fuel supply unit and supplies it to the main engine; a high-pressure fuel gas supply line connected from the GVT to the main engine and provided as a double pipe; an ejector that draws in gas present in the outer pipe of the double pipe to form a vacuum; a nitrogen supply unit that supplies compressed nitrogen gas as a driving fluid for the ejector; a vacuum suction line that draws the gas inside the outer pipe toward the ejector; a vacuum ejection line that discharges the gas drawn into the ejector through the vacuum suction line overboard; a nitrogen supply line that supplies the compressed nitrogen gas from the nitrogen supply unit to the ejector; and a three-way valve installed on the vacuum ejection line. A fuel gas supply system for a ship, comprising: a nitrogen filling line branched from the vacuum injection line at the point where the three-way valve is installed and connected to the outer pipe; wherein the double pipe of the high-pressure fuel gas supply line is formed in a vacuum state so that the outer pipe can be rapidly replaced with nitrogen gas when a fuel gas leak occurs in the inner pipe, and the three-way valve is switched in a direction toward the nitrogen filling line to fill the outer pipe with nitrogen gas supplied from the nitrogen supply unit to the ejector. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A fuel gas supply system for a ship according to claim 1, wherein the vacuum suction line and the nitrogen filling line are each connected to the ends of the high-pressure fuel gas supply line, and the connection points of the vacuum suction line and the nitrogen filling line are formed as far apart as possible to induce smooth circulation of the outer pipe. Claim 6 A fuel gas supply system for a ship according to claim 1, wherein the nitrogen supply unit supplies nitrogen gas as a purging gas for purging the main engine. Claim 7 A fuel gas supply system for a ship according to claim 6, further comprising a purging line for supplying nitrogen gas from the nitrogen supply unit for the purpose of purging the main engine, wherein the nitrogen gas supplied to the purging line is supplied to the main engine to purge the interior of the main engine and the high-pressure fuel gas supply line, and then discharged to the outside air through the GVT. Claim 8 A fuel gas supply system for a ship according to claim 7, wherein the fuel supply unit and the GVT are disposed within a Cargo Compressor Room, and the Cargo Compressor Room is located in the cargo area of ​​the ship. Claim 9 A fuel gas supply system for a ship according to claim 8, characterized in that the cargo compressor room is classified as a gas hazardous zone where periodic ventilation is performed. Claim 10 A fuel gas supply system for a ship according to claim 8, wherein the cargo area is located in front of the engine room of the stern section where the main engine is positioned. Claim 11 A fuel gas supply system for a ship according to claim 10, further comprising a cofferdam partitioned at the boundary between the engine room and the cargo area, wherein the high-pressure fuel gas supply line passes through the interior of the cofferdam, penetrates the front bulkhead of the engine room, and is connected to the main engine. Claim 12 A fuel gas supply system for a ship according to claim 11, wherein the cofferdam is characterized by performing periodic ventilation with respect to its internal space. Claim 13 A fuel gas supply system for a ship according to claim 12, further comprising: an exhaust fan installed on a first vent line for discharging air inside the cofferdam; and an e-ductor installed on a second vent line for discharging air inside the cofferdam, wherein ventilation inside the cofferdam is achieved by selectively operating the exhaust fan and the e-ductor individually or simultaneously. Claim 14 A fuel gas supply system for a ship according to claim 13, characterized in that, when the e-ductor is operated individually, the e-ductor is operated by receiving pressure from compressed nitrogen gas supplied from the nitrogen supply unit. Claim 15 A fuel gas supply system for a ship according to claim 14, characterized in that the exhaust fan can be eliminated when ventilation inside the cofferdam is performed using only the eductor. Claim 16 A fuel gas supply system for a ship according to claim 13, characterized in that, when the exhaust fan and the eductor are operated simultaneously, the eductor is operated by receiving at least one of the pressure formed by the exhaust fan and the pressure from the compressed nitrogen gas supplied from the nitrogen supply unit.

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