Nitrogen supply system for dual fuel engine and control method for same

Abstract

To provide a nitrogen supply system for a duel fuel engine capable of speedily purging and preventing backflow of gas.SOLUTION: A nitrogen supply system for a duel fuel engine includes: an engine unit driven by using fuel gas and provided as an engine for propulsion of a vessel; a fuel supply system for supplying fuel gas to an engine unit according to condition of the engine unit; a low pressure gas valve unit for controlling pressure and flow amount of the fuel gas supplied to the engine unit; a nitrogen supply unit for supplying nitrogen gas for purging inside of the engine unit; and an outside air exhaust unit for exhausting residue gas inside the engine unit to a safe section according to supply of the nitrogen gas.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to a gas purge system for a ship. Specifically, in the process of purging residual gas remaining inside an engine system that uses liquefied gas such as LNG as fuel, by applying a modified design with minimal placement of the piping through which the residual gas is discharged inside the engine room, the present invention relates to a gas purge system for a ship that maximizes safety from the risk of explosion.

Background Art

[0002] Generally, combustion devices such as engines installed in various ships use oils such as MDO (Marine Diesel Oil) and HFO (Heavy Fuel Oil) as fuel. However, such fuel oils have become the main culprit causing environmental pollution due to greenhouse gases and various harmful substances generated during combustion. In addition, when oil prices rise due to reasons such as depletion of fossil fuels and international political instability, problems in ship operation also occur, such as a sharp increase in fuel costs.

[0003] In recent years, regulations on air pollution have been gradually strengthened, and clean fuels such as liquefied natural gas (LNG) with low sulfur oxide (Sox) and nitrogen oxide (NOx) contents have attracted attention as energy sources to replace fuel oils. In LNGCs (LNG Carriers) that transport large amounts of LNG, technologies for using LNG stored in storage tanks as engine fuel have already been applied.

[0004] Recently, the use of LNG fuel has been gradually expanding to vessels other than LNGCs. In particular, its application to Very Large Crude-Oil Carriers (VLCCs) and Container Ships is being considered. Different from LNGCs that use LNG as fuel while directly loading it as cargo, general vessels need to install additional LNG fuel tanks to use LNG as fuel, and there are cases of operating LNG Fueled Ship (LFS) vessels equipped with separate LNG fuel tanks.

[0005] In addition, with recent technological developments, Dual Fuel Engines (DF Engines) that use both fuel oil and fuel gas as fuel have been developed and utilized. DF Engines are environmentally friendly engines that can significantly reduce fuel consumption, carbon emissions, and operating costs. They are a type of hybrid concept engine that uses heavy fuel oil (HFO) and natural gas for mixed fuel burning as fuel.

[0006] As an example, the ME-GI Engine is a 2-Stroke high-pressure gas injection engine that uses both heavy fuel oil and natural gas as fuel. Compared with diesel engines of the same output, it is attracting attention as a next-generation environmentally friendly engine that can reduce pollutant emissions, with carbon dioxide reduced by 23%, nitrogen compounds reduced by 80%, and sulfur compounds reduced by over 95%.

[0007] On the other hand, in the case of engines that use such fuel gas as fuel, when the engine system is not operated for a long time, when the inside of the system needs to be maintained, or when trying to switch the fuel used by the engine from fuel gas to fuel oil, if the fuel gas is not removed, it will remain in the system and pose a risk of explosion. Therefore, it is necessary to remove the fuel gas remaining inside the engine system, including the piping system that supplies fuel gas to the engine, for the safety of the system.

[0008] In the purge of a conventional co-firing engine system, during operation when the engine is supplied with fuel gas, the supply valve is open, the purge valve and the exhaust valve are closed, and while the opening degree of the pressure regulating valve is adjusted according to the engine load, fuel gas at an appropriate pressure is supplied to the engine.

[0009] Therefore, in a ship equipped with an engine using fuel gas, a gas purging system must be installed to discharge the fuel gas remaining in the engine system.

[0010] Generally, the gas purging system is configured to push out and discharge the fuel gas remaining in the engine system using an inert gas such as nitrogen (N2).

[0011] Figure 1 is a diagram schematically showing a conventional gas purging system of a ship.

[0012] Referring to Figure 1, an engine 1 using fuel gas in a conventional ship is connected to a fuel supply line 2 through which fuel gas is supplied from a fuel storage tank (not shown), and an exhaust line 3 through which exhaust gas is discharged from the engine 1, respectively. A gas valve unit 4 (GVU: Gas Valve Unit) is provided in the fuel supply line 2 to control the pressure and flow rate of the fuel gas supplied to the engine 1.

[0013] In addition, a purge line 6 for injecting nitrogen gas supplied from a nitrogen buffer tank 5 into the fuel supply line 2 is connected to purge the inside of the engine system.

[0014] The conventional gas purging system of a ship is configured to purge the inside of the fuel supply line 2 and the engine 1 using nitrogen gas supplied from the nitrogen buffer tank 5.

[0015] Specifically, when the purge operation of the engine system is started, the fuel supply valve 2-1 provided in the fuel supply line 2 is shut off, the purge valve 6-1 provided in the purge line 6 is opened, and nitrogen stored in the nitrogen buffer tank 5 is injected into the fuel supply line 2 in a gaseous state.

[0016] The nitrogen gas injected onto the fuel supply line 2 is supplied to the engine 1 via the gas valve unit 4, and the fuel gas remaining inside the engine system is pushed by the nitrogen gas and discharged to a safe area (e.g., the outside air) through the exhaust line 3.

[0017] Thus, it can be seen that in the conventional gas purge system of a ship, the purge with nitrogen gas is performed in the order of gas valve unit 4 → engine 1 → safe area.

[0018] However, in the conventional gas purge system as described above, there is a risk that the exhaust line 3 through which the residual gas is purged from the engine system is arranged inside the engine room, and a double pipe or duct treatment is required to provide a vent pipe inside the engine room classified as a gas safe zone, so there is a drawback that the YARD amount increases.

Summary of the Invention

Problems to be Solved by the Invention

[0019] The technical problem of the present invention is to apply a modified design in which the pipe through which the residual gas is discharged during the purge process of an engine system using liquefied gas such as LNG as fuel is minimized inside the engine room, and to provide a gas purge system for a ship that can ensure stability from the risk of explosion.

[0020] In addition, by integrating the valves provided to prevent the reverse flow of LNG gas in the gas purge system into one valve set, the logic for controlling reverse flow prevention is simplified, thereby improving the utilization rate of the space inside the ship and the effect of cost reduction.

[0021] Also, in the gas purge system, a reverse flow prevention valve set for the gas purge system that can more reliably prevent the reverse flow of LNG gas from the engine is provided.

[0022] In addition, by integrating the valves installed to prevent the reverse flow of LNG gas into one valve set, the logic for controlling reverse flow prevention is simplified, thereby improving the utilization rate of the space inside the ship and the effect of cost reduction.

[0023] Also, an object is to provide a nitrogen supply system for a dual-fuel engine and a control method thereof that enable rapid purging.

[0024] Also, an object is to provide a nitrogen supply system for a dual-fuel engine that prevents the reverse flow of gas and a control method thereof.

[0025] The technical problems of the present invention are not limited to the above-described technical problems, and other technical problems not described can be clearly understood by those of ordinary skill in the art from the following description.

Means for Solving the Problems

[0026] In order to achieve the above object, in one aspect of the present invention, in a ship equipped with an engine that uses fuel gas, a fuel supply line for supplying fuel gas to the engine; a gas valve unit installed in the fuel supply line to control the pressure of the fuel gas; a purge line for supplying nitrogen gas to the engine for the purpose of purging the inside of the engine and the inside of the fuel supply line; and the nitrogen gas supplied from the purge line is directly supplied to the engine to purge the inside of the engine and the fuel supply line, and then discharged to the outside air through the gas valve unit, and a gas purge system for a ship is provided.

[0027] It may further include a buffer tank for storing nitrogen gas supplied to the purge line.

[0028] The gas valve unit may be arranged within an area classified as a gas hazardous zone.

[0029] The gas hazardous zone is an area where ventilation is periodically performed, and may be a gas valve unit room (GVU Room) or a cargo compressor room (Cargo Compressor Room).

[0030] An exhaust line for discharging the residual gas discharged from the engine pushed by the nitrogen gas to the outside air is connected to the gas valve unit, and a purge valve for opening and closing the line may be provided on the exhaust line.

[0031] A backflow prevention valve set is provided on the purge line to prevent backflow of fuel gas from the engine, and the backflow prevention valve set may be arranged within the gas hazardous zone.

[0032] The backflow prevention valve set includes a first shut-off valve, a second shut-off valve, and a check valve that are sequentially provided from the upstream side on the purge line; and a bleed valve provided in a leakage discharge line that branches from the purge line between the first shut-off valve and the second shut-off valve to discharge leakage gas to the outside air. The first shut-off valve and the second shut-off valve have an opening / closing function, double-open / close or shut off the internal flow path of the purge line. The check valve allows the flow inside the purge line to flow only in one direction to prevent fuel gas from flowing back from the engine to the purge line side. The bleed valve functions to remove the residual pressure between the first shut-off valve and the second shut-off valve when the first shut-off valve and the second shut-off valve are shut off.

[0033] The first shut-off valve and the second shut-off valve operate so that their opening / closing states are always the same, and the bleed valve operates so that its opening / closing state is always opposite to that of the first shut-off valve and the second shut-off valve.

[0034] The backflow prevention valve set further includes an actuator for opening and closing the first shut-off valve, the second shut-off valve, and the bleed valve; a tube line for supplying an operating fluid for driving the actuator; and a solenoid valve unit in which solenoid valves provided in the tube line are grouped. The backflow prevention valve set is arranged in the gas valve unit room, the solenoid valve unit is arranged in the engine room so as to be close to a wall partitioning the gas valve unit room, and the tube line may be configured to penetrate and extend from the engine room to the gas valve unit room.

[0035] The engine includes a high-pressure gas injection engine that is driven by being supplied with fuel gas compressed at 10 bar or more, and a low-pressure gas injection engine that is driven by being supplied with fuel gas compressed at less than 10 bar. The gas valve unit includes a high-pressure gas valve unit that supplies fuel gas to the high-pressure gas injection engine, and a low-pressure gas valve unit that supplies fuel gas to the low-pressure gas injection engine. The purge line may be provided with a line connected from the buffer tank to the high-pressure gas injection engine and a line connected from the buffer tank to the low-pressure gas injection engine, respectively.

[0036] The backflow prevention valve set may be provided in the purge line connected to the high-pressure gas injection engine and the purge line connected to the low-pressure gas injection engine, respectively.

[0037] The high-pressure gas valve unit is arranged in the Cargo Compressor Room, and the low-pressure gas valve unit and the backflow prevention valve set may be arranged in the Gas Valve Unit Room (GVU Room).

[0038] To achieve the above object, one aspect of the present invention provides a nitrogen supply system for a dual fuel engine, which includes an engine unit driven by using fuel gas and provided as a propulsion engine of a ship, a fuel supply system that supplies the fuel gas according to the conditions of the engine unit, a low-pressure gas valve unit that controls the pressure and flow rate of the fuel gas supplied to the engine unit, a nitrogen supply unit that supplies nitrogen to purge the inside of the engine unit, and an outside air discharge unit that discharges the residual gas inside the engine unit to a safe area according to the nitrogen supply.

[0039] The fuel supply system and the engine unit are connected to a main fuel supply line, and the main fuel supply line may branch into a first fuel supply line and a second fuel supply line in the Gas Valve Unit Room.

[0040] A low-pressure gas valve unit section is arranged in the main fuel supply line. The low-pressure gas valve unit section includes a first low-pressure gas valve unit section and a second low-pressure gas valve unit section. The first low-pressure gas valve unit section and the second low-pressure gas valve unit section are arranged in a gas valve unit room (GVU room: Gas Valve Unit Room). The first low-pressure gas valve unit section is arranged in the first fuel supply line, and the second low-pressure gas valve unit section may be arranged in the second fuel supply line.

[0041] The low-pressure gas valve unit section includes a first piping purge valve, a second piping purge valve, an engine purge valve, a pressure regulating valve, a first shut-off valve, and a second shut-off valve. The first piping purge valve is arranged between the pressure regulating valve and the first shut-off valve. The second piping purge valve is arranged between the first shut-off valve and the second shut-off valve. The engine purge valve may be arranged at the rear end of the second shut-off valve.

[0042] The nitrogen supply section further includes a nitrogen supply adjustment section for adjusting the nitrogen supply to the engine section. The nitrogen supply adjustment section is connected to the nitrogen supply section and the first nitrogen supply line. The nitrogen supply adjustment section is arranged in a gas valve unit room (GVU Room: Gas Valve Unit Room). The engine section may be connected to the nitrogen supply adjustment section and the second nitrogen supply line.

[0043] The nitrogen supply adjustment section may include a first nitrogen shut-off valve and a second nitrogen shut-off valve for shutting off the nitrogen supply when a leak in the second nitrogen supply line is detected, a first nitrogen supply valve for adjusting the supply of nitrogen to the engine section, and a first backflow prevention valve for discharging the fuel gas to the outside and preventing backflow into the nitrogen supply line.

[0044] The engine unit is disposed above the second nitrogen supply line and includes a second nitrogen supply valve that is opened upon receiving a signal when nitrogen supply into the engine unit is required, a first pressure sensor disposed at the front end of the second nitrogen supply valve, a second backflow prevention valve that prevents the fuel gas from flowing backward in the second nitrogen supply line, and a second pressure sensor disposed between the second nitrogen supply valve and the second backflow prevention valve.

[0045] To achieve the above object, another aspect of the present invention provides a ship equipped with an engine using fuel gas, comprising: a storage tank for storing the fuel gas used as fuel for the engine in a liquefied state; a fuel supply line for supplying the fuel gas from the storage tank to the engine; a gas valve unit installed in the fuel supply line for controlling the pressure of the fuel gas; a buffer tank for storing an inert gas supplied for the purpose of purging the engine; and a purge line connecting the buffer tank to the engine. When the engine is driven using the fuel gas, the liquefied gas stored in the storage tank is supplied to the engine via the fuel supply line. When the engine is purged, the inert gas stored in the buffer tank is supplied to the engine to push out the gas remaining inside the engine, and the residual gas pushed out from the engine by the inert gas is discharged to the fuel supply line side and released to a safe area via the gas valve unit provided on the fuel supply line.

[0046] The direction in which the fuel gas is supplied from the storage tank to the engine is opposite to the direction in which the residual gas is discharged when the engine is purged.

[0047] To achieve the above object, another aspect of the present invention provides a backflow prevention valve set for a gas purge system installed in a purge line that supplies an inert gas for the purpose of purging a gas pipe. The backflow prevention valve set includes an integrated body, a first flow path formed inside the integrated body to provide a passage for the inflow and discharge of the inert gas, a second flow path branched from the first flow path to discharge leaked gas, a first shut-off valve and a second shut-off valve sequentially provided from the upstream side of the first flow path to doubly open or block the first flow path, a check valve provided on the downstream side of the second shut-off valve in the first flow path to allow the flow of the inert gas in the first flow path to only flow in one direction, and a bleed valve provided on the second flow path branched from the first flow path between the first shut-off valve and the second shut-off valve to remove the residual pressure between the first shut-off valve and the second shut-off valve when the first shut-off valve and the second shut-off valve are closed. The first shut-off valve, the second shut-off valve, the check valve, and the bleed valve are integrally configured as one valve set in the integrated body. A backflow prevention valve set for a gas purge system is provided, characterized in that it is configured as described above.

[0048] In the integrated body, an inert gas inlet for allowing the inert gas to flow into the first flow path, an inert gas outlet for discharging the inert gas supplied to the first flow path, and a leaked gas outlet for discharging the leaked gas discharged from the second flow path may be provided.

[0049] The backflow prevention valve set may further include a filter provided at the uppermost upstream side of the first flow path to filter foreign substances contained in the inert gas, and a pressure sensor provided in the first flow path between the filter and the first shut-off valve to measure the pressure of the inert gas at the corresponding point.

[0050] The first shut-off valve, the second shut-off valve, and the bleed valve are valves having an opening and closing function. The first shut-off valve and the second shut-off valve operate so that their opening and closing states are always the same, and the bleed valve operates so that its opening and closing state is always opposite to that of the first shut-off valve and the second shut-off valve.

[0051] The check valve may be of a closable type that can be shut off during maintenance.

[0052] The backflow prevention valve set may be provided in the first flow path between the first shut-off valve and the point where the second flow path branches, and may further include a sub-check valve that allows the flow of the inert gas in the first flow path to flow only in one direction.

[0053] The sub-check valve may be of a closable type that can be shut off during maintenance.

[0054] In addition, another aspect of the present invention for achieving the above object is a ship equipped with an engine using fuel gas, a purge line for supplying an inert gas to the engine for the purpose of purging the inside of the engine; and a backflow prevention valve set provided in the purge line to prevent backflow of fuel gas from the engine, the backflow prevention valve set including a first shut-off valve and a second shut-off valve that doubly open or shut off the internal flow path of the purge line, which are sequentially provided from the upstream side of the purge line, a check valve provided on the downstream side of the second shut-off valve in the purge line, and a bleed valve provided on a leakage discharge line that branches from the purge line between the first shut-off valve and the second shut-off valve and discharges gas leaked from the second shut-off valve, and is characterized in that it is composed of one valve set.

[0055] The purge line further includes an orifice provided on the downstream side of the backflow prevention valve set and a differential pressure gauge (Differential Pressure Transmitter) for measuring the pressure difference before and after the orifice. When the differential pressure through the orifice is measured to be equal to or greater than a predetermined value, it is determined that backflow has occurred from the engine to the purge line side, and an alarm is generated to trip the engine or switch the fuel of the engine from fuel gas to fuel oil.

[0056] To achieve the above object, another aspect of the present invention is a high-pressure gas injection engine driven by supplying liquefied gas as fuel, and a low-pressure gas injection engine driven by supplying liquefied gas at a lower pressure than the high-pressure gas injection engine as fuel; a first fuel supply line for compressing and vaporizing the liquefied gas stored in the liquefied gas storage tank and supplying it to the high-pressure gas injection engine, a second fuel supply line for compressing and vaporizing the liquefied gas stored in the liquefied gas storage tank and supplying it to the low-pressure gas injection engine, a first purge line for supplying an inert gas to the high-pressure gas injection engine for the purpose of purging the inside of the high-pressure gas injection engine and the first fuel supply line, and a second purge line for supplying an inert gas to the low-pressure gas injection engine for the purpose of purging the inside of the low-pressure gas injection engine and the second fuel supply line. The inert gas supplied to the first purge line and the second purge line is directly supplied to the high-pressure gas injection engine and the low-pressure gas injection engine respectively. The purge of the high-pressure gas injection engine is performed in the direction from the inside of the high-pressure gas injection engine to the first fuel supply line side, and the purge of the low-pressure gas injection engine is performed in the direction from the inside of the low-pressure gas injection engine to the first fuel supply line side. A gas purge system for a ship is provided.

[0057] The residual gas inside the high-pressure gas injection engine pushed and discharged by the inert gas supplied to the high-pressure gas injection engine through the first purge line is discharged to the outside air through a high-pressure gas valve unit provided in the first fuel supply line. The residual gas inside the low-pressure gas injection engine pushed and discharged by the inert gas supplied to the low-pressure gas injection engine through the second purge line is discharged to the outside air through a low-pressure gas valve unit provided in the second fuel supply line.

[0058] The high-pressure gas valve unit is a device for controlling the pressure and flow rate of the fuel gas supplied to the high-pressure gas injection engine, and is arranged in the cargo compressor room (Cargo Compressor Room) or the gas valve unit room (GVU Room) classified as a gas dangerous area. The low-pressure gas valve unit can be arranged in the gas valve unit room as a device for controlling the pressure and flow rate of the fuel gas supplied to the low-pressure gas injection engine.

[0059] The line from the cargo compressor room or the gas valve unit room where the high-pressure gas valve unit is arranged to the high-pressure gas injection engine in the first fuel supply line is provided with a double pipe, and the line from the gas valve unit room where the low-pressure gas valve unit is arranged to the low-pressure gas injection engine in the second fuel supply line can be provided with a double pipe.

[0060] It may further include a first check valve set installed in the first purge line to prevent the backflow of fuel gas from the high-pressure gas injection engine, and a second check valve set provided in the second purge line to prevent the backflow of fuel gas from the low-pressure gas injection engine.

[0061] It further includes a third purge line branched from the first purge line at the rear end of the first check valve set and connected to the second fuel supply line. The inert gas supplied through the third purge line purges the inside of the second fuel supply line from the rear end of the master valve installed in the second fuel supply line to control the supply of fuel gas to the low-pressure gas injection engine side to the point where the low-pressure gas valve unit is installed.

[0062] The first backflow prevention valve set includes: a first flow path that forms a flow path for an inert gas inside; a first shut-off valve and a second shut-off valve that are sequentially provided on the first flow path to open and close the first flow path; a check valve provided at the rear end of the second shut-off valve in the first flow path; a second flow path that branches from the first flow path between the first shut-off valve and the second shut-off valve to discharge leaked gas; and a bleed valve installed on the second flow path.

[0063] When the high-pressure gas injection engine operates in gas mode, the first shut-off valve and the second shut-off valve in the first backflow prevention valve set are shut off, the bleed valve is opened, and when purging the high-pressure gas injection engine, the first shut-off valve and the second shut-off valve in the first backflow prevention valve set are opened, and the bleed valve is shut off.

[0064] The second purge line may further include a nitrogen supply valve and a check valve that are sequentially provided between the second backflow prevention valve set and the low-pressure gas injection engine.

[0065] When the low-pressure gas injection engine operates in gas mode, the second backflow prevention valve set is controlled so that the second purge line is in an open state, and the second purge line up to the point where the nitrogen supply valve is installed receives the supply pressure of the inert gas.

[0066] The first backflow prevention valve set further includes a first pressure sensor provided at the front end of the nitrogen supply valve. When the supply pressure of the inert gas measured by the first pressure sensor drops below a predetermined value, the gas mode operation of the low-pressure gas injection engine can be stopped.

[0067] The first backflow prevention valve set further includes a second pressure sensor provided between the nitrogen supply valve and the check valve. The second pressure sensor can detect an increase in pressure when backflow occurs from the low-pressure gas injection engine and stop the gas mode operation of the low-pressure gas injection engine.

[0068] The second backflow prevention valve set includes: a first flow path that forms a flow path for an inert gas inside; a first shut-off valve and a second shut-off valve that are sequentially provided on the first flow path to open and close the first flow path; a check valve provided at the rear end of the second shut-off valve on the first flow path; a second flow path that branches from the first flow path between the first shut-off valve and the second shut-off valve to discharge leaked gas; and a bleed valve installed on the second flow path.

[0069] When the low-pressure gas injection engine operates in gas mode, the first shut-off valve and the second shut-off valve in the second backflow prevention valve set are opened, the nitrogen supply valve and the bleed valve are shut off, and when the low-pressure gas injection engine stops operating in gas mode, the first shut-off valve and the second shut-off valve in the second backflow prevention valve set are shut off, and the bleed valve may be opened.

[0070] During purging of the low-pressure gas injection engine, the first shut-off valve, the second shut-off valve, and the nitrogen supply valve in the second backflow prevention valve set may be opened, and the bleed valve may be shut off.

[0071] One or more actuators for controlling the opening and closing of the first shut-off valve, the second shut-off valve, and the bleed valve; a solenoid valve group for supplying an operating fluid to operate the actuator; a tube line for supplying the operating fluid from the solenoid valve group to the actuator; and a solenoid valve installed on the tube line to control the pressure of the operating fluid may be further provided.

[0072] The tube line is provided corresponding to the number of the actuators, and a single solenoid valve may be provided on a line in which the tube lines are integrated.

[0073] The first shut-off valve, the second shut-off valve, the check valve, the bleed valve, and the solenoid valve may be integrally configured in one body and manufactured as an integrated set.

[0074] To achieve the above object, another aspect of the present invention provides a nitrogen supply system for a dual fuel engine, which includes an engine unit driven by fuel gas and provided as a propulsion engine for a ship, a fuel supply unit that supplies the fuel gas according to the conditions of the engine unit, a low-pressure gas valve unit that controls the pressure and flow rate of the fuel gas supplied to the engine unit, a nitrogen supply unit that supplies nitrogen to purge the interior of the engine unit, and an outside air discharge unit that discharges residual gas inside the engine unit to a safe area according to the nitrogen supply.

[0075] The fuel supply unit and the engine unit are connected to a main fuel supply line, and the main fuel supply line may branch into a first fuel supply line and a second fuel supply line in a gas valve unit room.

[0076] The low-pressure gas valve unit is arranged on the main fuel supply line. The low-pressure gas valve unit includes a first low-pressure gas valve unit and a second low-pressure gas valve unit. The first low-pressure gas valve unit and the second low-pressure gas valve unit are arranged in a gas valve unit room (GVU room: Gas Valve Unit Room). The first low-pressure gas valve unit may be arranged on the first fuel supply line, and the second low-pressure gas valve unit may be arranged on the second fuel supply line.

[0077] The low-pressure gas valve unit includes a first pipe purge valve, a second pipe purge valve, an engine purge valve, a pressure regulating valve, a first shut-off valve, and a second shut-off valve. The first shut-off valve is arranged between the pressure regulating valve and the first shut-off valve. The second pipe purge valve is arranged between the first shut-off valve and the second shut-off valve. The engine purge valve may be arranged at the rear end of the second shut-off valve.

[0078] The nitrogen supply unit further includes a nitrogen supply adjustment unit that adjusts the supply of nitrogen to the engine unit. The nitrogen supply adjustment unit is connected to the nitrogen supply unit and the first nitrogen supply line, and is arranged in the Gas Valve Unit Room (GVU Rom). The engine unit is connected to the nitrogen supply adjustment unit and the second nitrogen supply line.

[0079] The nitrogen supply adjustment unit may include a first nitrogen shut-off valve and a second nitrogen shut-off valve that shut off the nitrogen supply when a leak in the second nitrogen supply line is detected, a first nitrogen supply valve that adjusts the supply of nitrogen to the engine unit, and a first backflow prevention valve that discharges the fuel gas to the outside and prevents backflow into the nitrogen supply line.

[0080] The engine unit may include a second nitrogen supply valve that is arranged in the second nitrogen supply line and is opened upon receiving a signal when nitrogen supply into the engine unit is required, a first pressure sensor arranged at the front end of the second nitrogen supply valve, a second backflow prevention valve that prevents the fuel gas from flowing back in the second nitrogen supply line, and a second pressure sensor arranged between the second nitrogen supply valve and the second backflow prevention valve.

[0081] To achieve the above object, another aspect of the present invention provides a control method for a nitrogen supply system of a dual fuel engine, including controlling the supply of fuel gas from a fuel supply unit to an engine unit, and controlling the opening and closing of a nitrogen supply adjustment unit according to the supply of the fuel gas. The step of controlling the opening and closing of the nitrogen supply adjustment unit includes an opening step and a closing step.

[0082] The opening step may be to supply fuel gas and nitrogen gas, open the first nitrogen shut-off valve, the second nitrogen shut-off valve, and the first nitrogen supply valve of the nitrogen supply adjustment unit, and close the first backflow prevention valve and the second nitrogen supply valve.

[0083] The step of opening further includes a step of measuring pressure. When it is determined that fuel gas flows backward if the pressure of the second pressure sensor rises, the fuel gas supply is stopped, the first nitrogen shut-off valve and the second nitrogen shut-off valve are closed, and the first backflow prevention valve and the second nitrogen supply valve are opened to discharge the fuel gas to a safe area.

[0084] The step of opening further includes a purging step of stopping the supply of fuel gas and purging with nitrogen. The nitrogen purging step may include opening the second nitrogen supply valve, the second shut-off valve, and the engine purge valve, closing the first shut-off valve, and purging the engine section, the first fuel supply line, and the second fuel supply line.

[0085] The nitrogen purging step may include opening the second nitrogen supply valve, the second shut-off valve, the first pipe purge valve, and the second pipe purge valve, closing the first shut-off valve and the engine purge valve, and purging the engine section, the first fuel supply line, and the second fuel supply line.

[0086] The step of closing may include closing the nitrogen supply adjustment unit to stop the nitrogen supply if the pressure of the second pressure measurement sensor is higher than the pressure of the first pressure measurement sensor, or if the pressure of the nitrogen supply unit is 5 Bar or less.

Advantages of the Invention

[0087] The present invention configured as described above applies a modified design of a gas purge system in which piping through which residual gas is discharged during the purge process of an engine system using liquefied gas such as LNG as fuel is minimized inside the engine room. Therefore, it is possible to maximize stability from the risk of explosion and reduce the YARD amount, resulting in a significant improvement in productivity in shipbuilding.

[0088] In addition, by integrating the valves installed to prevent the backflow of LNG gas in the gas purge system into one valve set, the logic of backflow prevention control is simplified, and thus there are advantageous effects in terms of the utilization rate of the ship's internal space and cost reduction.

[0089] In addition, the present invention provides further stability in the operation of the engine system and the gas purge system by providing an orifice and a differential pressure gauge on the system for preventing the backflow of LNG gas.

[0090] In addition, by changing the purge order of the residual gas remaining inside the engine system that uses liquefied gas such as LNG as fuel, there is an effect that the gas piping arranged inside the engine room is reduced and the stability is maximized.

[0091] In addition, there is an effect of providing a nitrogen supply system for a dual fuel engine and a control method thereof.

[0092] In addition, there is an effect of providing a nitrogen supply system for a dual fuel engine and a control method thereof, which can purge very quickly while the nitrogen gas is pressurizing the engine part.

[0093] In addition, there is an effect of providing a nitrogen supply system for a dual fuel engine that prevents the backflow of gas and a control method thereof.

[0094] In addition, by applying one nitrogen supply adjustment unit to a plurality of engines, there is an effect of reducing the volume occupied by the ship.

[0095] In addition, since the nitrogen gas is directly supplied to the engine part and the residual gas inside the engine part is discharged through the low-pressure gas valve unit part, there is no need to provide another belt pipe inside the engine room, and there is an effect of reducing the YARD amount compared to the prior art.

[0096] In addition, since the pipe through which the residual gas is purged and discharged from the engine section is arranged in the Gas Valve Unit room (GVU room), the gas pipes arranged inside the engine room can be significantly reduced, and there is an effect of maximizing stability.

[0097] The technical problems of the present invention are not limited to the above-described technical problems, and other technical problems not mentioned can be clearly understood by those skilled in the art from the following description.

Brief Description of the Drawings

[0098]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0099] Details regarding the object, technical configuration, operation, and effects of the present invention can be more clearly understood through a detailed description based on the accompanying drawings of the specification of the present invention.

[0100] The terms in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. For example, when a component in this specification is described as "including" or "comprising", it means that, unless otherwise stated to the contrary, it does not exclude other components but may further include or comprise other components. Furthermore, when there is a description that a certain component is "connected" or "joined" to another component, it should be understood that it may be directly connected or joined to the other component, but other components may exist in between.

[0101] The "liquefied gas" described in this specification can include all liquefied gases that can be liquefied at low temperatures for storage and transportation and supplied as fuel for an engine in a vaporized state, such as LNG, LPG (Liquefied Petroleum Gas), LEG (Liquefied Ethane Gas), Liquefied Ethylene Gas, Liquefied Propylene Gas, etc. However, for the sake of explanation in the following specification, LNG, which is a typical liquefied gas, will be used as an example for explanation.

[0102] In addition, in this specification, "ship" is construed as a concept including all types of ships that use liquefied gas as fuel for the propulsion engine. Typically, it includes self-propelled ships such as LFS (LNG Fueled Ship) that is propelled using LNG as fuel, LNGC (LNG Carrier) that uses LNG stored in the storage tank or the evaporation gas generated in the storage tank as fuel for the engine among ships that transport LNG, and also includes offshore floating structures such as LNG FPSO (Floating Production Storage Offloading) and LNG FSRU (Floating Storage Regasification Unit).

[0103] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are provided so that those skilled in the art can easily understand the technical idea of the present invention, and it should not be construed that the present invention is limited thereby. Naturally, the embodiments of the present invention can be variously applied by ordinary technicians in the relevant field.

[0104] FIG. 2 is a diagram schematically showing a gas purge system of a ship according to an embodiment of the present invention. FIG. 3 is a piping diagram of a portion where a backflow prevention valve set is provided in the gas purge system of the ship according to the present embodiment.

[0105] Referring to FIG. 2, the gas purge system of the ship according to the present embodiment includes an engine 100 that uses liquefied gas such as LNG as fuel, gas valve units (GVU: Gas Valve Unit) 210 and 220 that control the pressure and flow rate of the fuel gas supplied to the engine 100, the engine 100, and a buffer tank 300 that supplies an inert gas to purge the inside of the line through which the fuel gas is supplied to the engine 100.

[0106] The engine 100 of the present embodiment is an engine that can be driven using LNG as fuel, and also includes a DF engine (Dual Foul Engent) that can use both heavy oil and natural gas as fuel.

[0107] In addition, the engine 100 of the present embodiment may include a high-pressure gas injection engine 110 that is driven by being supplied with LNG gas compressed at a high pressure, and a low-pressure gas injection engine 120 that is driven by being supplied with LNG gas compressed at a low pressure.

[0108] The high-pressure gas injection engine 110 can be driven by being supplied with LNG gas compressed and vaporized to 10 bar or more, and can be a propulsion engine such as an ME-GI engine.

[0109] The low-pressure gas injection engine 120 can be driven by being supplied with LNG gas compressed and vaporized at less than 10 bar, and can be a general DF generator engine such as a DFDG (Dual Fuel Diesel Generator) or a propulsion engine such as an X-DF (eXtreme Dual Fuel).

[0110] The high-pressure gas injection engine 110 and the low-pressure gas injection engine 120 are arranged in an engine room partitioned on the stern side of the ship.

[0111] In addition, the ship of the present embodiment can be provided with an LNG storage tank (not shown) for storing LNG gas (natural gas) supplied to the engine 100 in a liquefied state, and the LNG stored in the LNG storage tank can be compressed and vaporized by a fuel gas supply system (FGSS) 400 and supplied as fuel for the engine 100.

[0112] The fuel supply system 400 can include a vaporizer for forcibly vaporizing LNG, a compressor for compressing LNG gas to the pressure required by the engine, etc., and is usually arranged in a cargo compressor room.

[0113] The LNG gas compressed and vaporized in the fuel supply system 400 is supplied to the engine 100 along the fuel supply lines L1 and L2. Since the high-pressure gas injection engine 110 and the low-pressure gas injection engine 120 have different required pressures and temperatures, the first fuel supply line L1 connected to the high-pressure gas injection engine 110 and the second fuel supply line L2 connected to the low-pressure gas injection engine 120 are provided as separate lines respectively.

[0114] Specifically, the LNG gas compressed and vaporized to high pressure in the fuel supply system 400 is supplied to the high-pressure gas injection engine 110 along the first fuel supply line L1, and the LNG gas compressed and vaporized to low pressure is supplied to the low-pressure gas injection engine 120 along the second fuel supply line L2.

[0115] In a ship using LNG as fuel in this way, LNG gas is supplied to the engines 110 and 120 through a pipe connected from the LNG storage tank, and gas valve units 210 and 220 are provided in the lines L1 and L2 through which the LNG gas is supplied to the engines 110 and 120.

[0116] The gas valve units 210 and 220 are devices that group valves for controlling the pressure and flow rate of the LNG gas supplied to the engine 100. They are provided between the engine 100 and the LNG storage tank to supply the LNG gas at a pressure corresponding to the load of the engine 100, and include a filter, a gas supply valve, a gas flow meter, etc.

[0117] In this embodiment, the gas valve units 210 and 220 may include a high-pressure gas valve unit 210 for controlling the LNG gas supplied to the high-pressure gas injection engine 110 and a low-pressure gas valve unit 220 for controlling the LNG gas supplied to the low-pressure gas injection engine 120.

[0118] The high-pressure gas valve unit 210 is installed in the first fuel supply line L1 and is usually arranged in the cargo compressor room as shown in the figure. However, it can also be arranged together with the low-pressure gas valve unit 220 in the gas valve unit room (GVU room) described later.

[0119] The low-pressure gas valve unit 220 is installed on the second fuel supply line L2 and can be arranged in the gas valve unit room. The gas valve unit room is located in a separately provided area away from the engine room and can be arranged behind the engine room on the stern side as shown in the figure. It is of course also possible to arrange the low-pressure gas valve unit 220 together with the high-pressure gas valve unit 210 in the cargo compressor room.

[0120] The aforementioned cargo compressor room and gas valve unit room are spaces classified as Gas Hazardous Zones and are spaces for handling vaporized LNG gas. Therefore, periodic ventilation is required for safety. Normally, it is necessary to be able to exchange dry air 30 times per hour to prepare for gas leakage. Therefore, an exhaust fan f (Ventilation Fan) may be provided in the cargo compressor room and gas valve unit room so that ventilation can always be carried out.

[0121] On the other hand, in the first fuel supply line L1, it is preferable that at least the line from the cargo compressor room (or from the gas valve unit room if the high-pressure gas valve unit 210 is provided in the gas valve unit room) to the high-pressure gas injection engine 110 is composed of a double pipe, and the inside of the double pipe is configured to exchange air 30 times per hour.

[0122] Similarly, in the second fuel supply line L2, it is preferable that at least the line from the gas valve unit room to the low-pressure gas injection engine 120 is composed of a double pipe, and the inside of the double pipe is configured to exchange air 30 times per hour.

[0123] The buffer tank 300 stores an engine 100 and an inert gas that is supplied to purge the interiors of fuel supply lines L1 and L2 through which LNG gas is supplied to the engine 100. Generally, nitrogen (N2) is used as the inert gas, and the following description will continue using nitrogen as an example.

[0124] For the ship of this embodiment, a nitrogen generator (not shown) can be separately provided to use nitrogen as the purge gas. The nitrogen generated by the nitrogen generator is temporarily stored in the buffer tank 300 and then supplied when purging the engine system.

[0125] The buffer tank 300 can be arranged inside the engine room. The engine room is classified as a Gas Safe Zone, which is an area where it is necessary to ensure safety from the gas dangerous area. For example, direct access from the gas dangerous area to the gas safe area is prohibited (an Air Lock is installed if necessary), and the fuel supply pipe passing through the gas safe area needs to be completely enclosed by a double pipe or duct.

[0126] A purge line PL can be connected to supply nitrogen gas from the buffer tank 300 to the engine 100 side. The purge line PL can be provided with a line connecting from the buffer tank 300 to the high-pressure gas injection engine 110 and a line connecting to the low-pressure gas injection engine 120, respectively.

[0127] And, a backflow prevention valve set 500 can be provided on the purge line PL to prevent the LNG gas inside the engine 100 from flowing back to the buffer tank 300 side.

[0128] The backflow prevention valve set 500 may be configured and installed as one set per engine, or only two sets may be installed separately for the main engine provided for ship propulsion and the generator engine provided for generating necessary electric power inside the ship.

[0129] The backflow prevention valve set 500 is arranged in a gas dangerous area where the air is exchanged 30 times per hour together with the gas valve unit room. However, the present invention is not limited to this, and it is also possible to arrange the backflow prevention valve set 500 in a cargo compressor room or other gas dangerous areas. However, the backflow prevention valve set 500 is preferably arranged as close as possible to the engine 100 and the buffer tank 300 in order to reduce the amount of material. Therefore, in the present invention, as shown in the figure, it is considered most preferable to arrange the backflow prevention valve set 500 in the gas valve unit room.

[0130] The specific configuration of the backflow prevention valve set 500 will be described in more detail later.

[0131] The nitrogen gas supplied from the buffer tank 300 to purge the engine system pushes out the residual gas in the engine 100, and the residual gas and nitrogen gas pushed out from the engine 100 are discharged to a safe area (e.g., outside air) through the gas valve units 210, 220.

[0132] A vent line VL for discharging the residual gas and nitrogen gas discharged from the engine 100 to a safe area is connected to the gas valve units 210, 220, and a purge valve PV for opening and closing the line can be installed on the vent line VL respectively.

[0133] The purge operations on the high-pressure gas injection engine 110 and low-pressure gas injection engine 120 sides are described separately below.

[0134] When purging the high-pressure gas injection engine 110 side, first, the supply of LNG gas from the fuel supply system 400 to the high-pressure gas injection engine 110 side is stopped. Then, nitrogen gas is supplied from the buffer tank 300 into the high-pressure gas injection engine 110, and the purge valve PV of the vent line VL connected to the high-pressure gas valve unit 210 is opened. The residual gas pushed out from the high-pressure gas injection engine 110 by the nitrogen gas supplied from the buffer tank 300 is discharged to the safe area through a part of the first fuel supply line L1 and via the high-pressure gas valve unit 210 together with the nitrogen gas.

[0135] The purge of the low-pressure gas injection engine 120 side is performed in the same manner. When purging the low-pressure gas injection engine 120, first, the supply of LNG gas from the fuel supply system 400 to the low-pressure gas injection engine 120 side is stopped. Then, nitrogen gas is supplied from the buffer tank 300 into the low-pressure gas injection engine 120, and the purge valve PV of the vent line VL connected to the low-pressure gas valve unit 220 is opened. The residual gas pushed out from the low-pressure gas injection engine 120 by the nitrogen gas supplied from the buffer tank 300 is discharged to the safe area through a part of the second fuel supply line L2 and via the low-pressure gas valve unit 220 together with the nitrogen gas.

[0136] According to the above, different from injecting nitrogen gas into the fuel supply line to purge the inside of the conventional engine system, nitrogen gas is directly supplied to the engine 100 side, and the residual gas inside the engine system is purged from the engine 100 to the gas valve units 210 and 220 sides.

[0137] That is, conventionally (refer to FIG. 1), the purge of the engine system is performed in the order of the gas valve unit 4 → the engine 1 → the safe area, while in the present invention, the purge of the engine system is performed in the order of the engine 100 → the gas valve units 210 and 220 → the safe area.

[0138] In addition, in the present invention, the direction in which LNG gas is supplied as fuel for the engine 100 is opposite to the direction for purging the inside of the engine system.

[0139] According to this, nitrogen gas is directly injected from the buffer tank 300 into the engine 100, and the residual gas in the engine 100 is discharged through the gas valve units 210 and 220. Therefore, there is no need to separately provide a vent pipe inside the engine room, and there is an effect of reducing the YARD amount compared to the conventional case.

[0140] In addition, since most of the pipes through which the residual gas is purged and discharged from the engine 100 are arranged in the gas valve unit room or the cargo compressor room, the gas pipes arranged inside the engine room can be significantly reduced, and there is an effect of maximizing stability. Since there are many electrical equipment, devices for handling oils, ignition devices, etc. in the engine room, it is better not to arrange the gas pipes in the engine room as much as possible. In addition, since the gas valve unit room (gas dangerous area) is designed assuming the possibility of gas leakage, air exchange is carried out 30 times per hour, so it is very advantageous for ventilation to discharge the residual gas of the engine system using this area. Furthermore, when purging is performed from the engine 100 to the gas valve units 210 and 220 side, the residual gas is discharged through the fuel supply lines L1 and L2 which are already composed of double pipes. Therefore, the utilization rate of the existing equipment is increased, and there is no need to additionally install a separate double pipe for discharging the residual gas, which is also preferable in terms of cost.

[0141] On the other hand, in ships such as LNGC and LFS, when the pipes for purging the engine system are directly connected, a check valve is installed to prevent the fuel gas inside the engine system from flowing back to the nitrogen supply section. In addition, a double block valve and a bleed valve are installed, and a configuration capable of remote control is required by the classification society.

[0142] These requirements are already mandatory for application in IGF-CODE, and since an increase in LFS ships is expected in the future, the application of the relevant items is mandatory.

[0143] However, valves such as those described above must always be installed in a gas hazardous area, and explosion protection needs to be applied to prevent explosions, which incurs considerable costs. Therefore, installing three expensive valves for each point where the said point (the part where the purge pipe is directly connected) occurs is expected to have a significant impact on the construction cost of the ship.

[0144] Therefore, in the present invention, a concept of configuring a double block valve, a bleed valve, and a check valve in one valve set (Valve Set) has been developed. Hereinafter, the specific structure of the backflow prevention valve set 500 configured with one valve set by applying the said concept will be described.

[0145] Referring to FIG. 3, the backflow prevention valve set 500 according to an embodiment of the present invention includes a first shut-off valve 510, a second shut-off valve 520, and a check valve 530 that are sequentially provided on a purge line PL for supplying nitrogen gas from a buffer tank 300 to the engine 100 side.

[0146] And the backflow prevention valve set 500 of the present embodiment may further include a leakage discharge line LL branched from the purge line PL between the first shut-off valve 510 and the second shut-off valve 520, and a bleed valve 540 provided on the leakage discharge line LL.

[0147] The first shut-off valve 510 and the second shut-off valve 520 are valves that open or block the internal flow path of the purge line PL, and can be valves having an opening and closing function such as a ball valve, for example.

[0148] The first shut-off valve 510 and the second shut-off valve 520 are sequentially provided on the upstream side and the downstream side of the purge line PL, respectively, and by always performing opening and closing simultaneously, the flow of nitrogen gas is blocked or opened doubly.

[0149] The first shut-off valve 510 and the second shut-off valve 520 are opened only when nitrogen gas is supplied from the buffer tank 300 to the engine 100 side, and maintain a closed state during normal times.

[0150] The check valve 530 is provided on the most downstream side of the purge line PL to prevent the backflow of LNG gas from the engine 100 side.

[0151] Although the check valve 530 is always in an open state, it functions to allow fluid to flow in only one direction, thus primarily preventing the backflow of LNG gas from the engine 100 side.

[0152] In this embodiment, the check valve 530 can be a closable check valve that can be shut off for maintenance purposes.

[0153] The bleed valve 540 is provided between the first shut-off valve 510 and the second shut-off valve 520, and serves to remove the residual pressure inside when the first shut-off valve 510 and the second shut-off valve 520 are shut off.

[0154] The bleed valve 540 is normally always open, and when a leak occurs in the second shut-off valve 520, it discharges the leaked gas between the first shut-off valve 510 and the second shut-off valve 520 to a safe area. At this time, since the first shut-off valve 510 blocks the leaked gas again, there is an effect of doubly preventing the backflow from the engine 100 side.

[0155] The bleed valve 540 is shut off when the first shut-off valve 510 and the second shut-off valve 520 are opened. That is, the opening and closing operations of the first and second shut-off valves 510, 520 and the bleed valve 540 are always opposite.

[0156] On the one hand, the backflow prevention valve set 500 can further include actuators for opening and closing the first and second shut-off valves 510, 520 and the bleed valve 540, and a tube line TL for supplying compressed air (or hydraulic oil) for driving the actuators is connected, and a solenoid valve SV can be provided in the tube line TL.

[0157] When there are a plurality of tube lines TL, a plurality of corresponding solenoid valves SV are also provided for each tube line TL, and the plurality of solenoid valves SV are collectively named a solenoid valve unit 600 (Solenoid Valve Unit).

[0158] At this time, since the solenoid valve unit 600 is not a line handling gas, there is no need to specifically design it for explosion protection. However, when it is arranged inside the gas valve unit room, due to the reason that it is an electrical component, it is necessary to apply an expensive explosion protection device, which is not preferable in terms of cost.

[0159] Therefore, in this embodiment, as shown in FIG. 2, the solenoid valve unit 600 is arranged in the gas safe zone inside the engine room at the position closest to the wall partitioning the gas valve unit room, and only the tube line TL is configured to penetrate and extend into the gas valve unit room. Such a configuration can apply a general solenoid valve without an expensive explosion protection device, which is advantageous in terms of cost.

[0160] Further, the backflow prevention valve set 500 can further include an orifice 710 (Orifice) provided on the downstream side of the check valve 530 in the purge line PL, and a differential pressure gauge (DTP: Differential Pressure Transmitter) 720 for measuring the pressure difference before and after the orifice 710. When LNG gas flows back from the engine 100 side and a differential pressure is generated through the orifice 710, further stability can be achieved by tripping the engine 100.

[0161] As described above, the backflow prevention valve set 500 is configured such that the opening and closing operations of the three valves 510, 520, and 530 are interlocked with each other, and by utilizing such characteristics, the valves 510, 520, and 530 are configured to operate the corresponding functions with a single actuator.

[0162] That is, since the operations of the first and second shut-off valves 510, 520 and the bleed valve 540 are always opposite, the first and second shut-off valves 510, 520 and the bleed valve 540 can be connected to a single actuator with only the direction reversed, enabling a configuration that operates at once.

[0163] Hereinafter, the specific content of the configuration in which the opening and closing operations of the first and second shut-off valves 510, 520 and the bleed valve 540 are performed by a single actuator will be described for each embodiment.

[0164] FIG. 4 is a diagram showing a first embodiment of the backflow prevention valve set according to the present invention. FIG. 5 is a diagram showing a second embodiment of the backflow prevention valve set according to the present invention. The LNG gas pipe shown in FIGS. 4 and 5 is a pipe provided inside the engine 100 of FIG. 2.

[0165] Referring to FIG. 4, the backflow prevention valve set 500 of the first embodiment may further include a reciprocating actuator 580 that controls the opening and closing of the first shut-off valve 510, the second shut-off valve 520, and the bleed valve 540.

[0166] The reciprocating actuator 580 is driven hydraulically or pneumatically, and may include a first power transmission unit 551 connected to the first shut-off valve 510 and the second shut-off valve 520, and a second power transmission unit 552 connected to the bleed valve 540.

[0167] The first power transmission unit 551 and the second power transmission unit 552 are transmitted the power of a piston that reciprocates inside the cylinder of the reciprocating actuator 580, and open and close the valves 510, 520, 540.

[0168] At this time, the first and second shut-off valves 510 and 520 connected to the first power transmission unit 551 and the bleed valve 540 connected to the second power transmission unit 552 can be provided in opposite directions, and the opening and closing directions of the first and second shut-off valves 510 and 520 by the first power transmission unit 551 and the opening and closing direction of the bleed valve 540 by the second power transmission unit 552 operate in opposite directions to each other.

[0169] As an example, when the working fluid is supplied from the lower part of the reciprocating actuator 580, the piston inside the cylinder is pushed upward, the first power transmission unit 551 transmits the movement of the piston to open the first and second shut-off valves 510 and 520, and the second power transmission unit 552 transmits the movement of the piston to operate so as to block the bleed valve 540.

[0170] Conversely, when the working fluid is supplied from the upper part of the reciprocating actuator 580, the piston inside the cylinder descends, the first power transmission unit 551 transmits the movement of the piston to block the first and second shut-off valves 510 and 520, and the second power transmission unit 552 transmits the movement of the piston to operate so as to open the bleed valve 540.

[0171] That is, in the first embodiment, the reciprocating actuator 580 is configured such that the first and second shut-off valves 510 and 520 and the bleed valve 540 always operate in opposite states.

[0172] The reciprocating actuator 580 of the first embodiment can be configured not only hydraulically but also pneumatically, and it is also possible to use other devices for controlling the opening and closing of the valves. Furthermore, other mechanical methods can also be applied to the first power transmission unit 551 and the second power transmission unit 552.

[0173] Next, referring to FIG. 5, the backflow prevention valve set 500 of the second embodiment includes the same configuration as the first embodiment, except that the reciprocating actuator 580 is replaced by a rotary actuator 560. Therefore, the description of the configuration and content overlapping with the first embodiment will be omitted.

[0174] The rotary actuator 560 may include a spindle gear 564 that rotates in a clockwise or counterclockwise direction by a motor or other rotary drive unit, a first power transmission unit 561 to which the rotational power of the spindle gear 564 is transmitted to open and close the first shut-off valve 510, a second power transmission unit 562 to which the rotational power of the spindle gear 564 is transmitted to open and close the second shut-off valve 520, and a third power transmission unit 563 to which the rotational power of the spindle gear 564 is transmitted to open and close the bleed valve 540.

[0175] The first to third power transmission units 561, 562, 563 are transmitted with the rotational movement of the spindle gear 564 and use the rotational force to open and close the valves 510, 520, 540.

[0176] At this time, the first power transmission unit 561 and the second power transmission unit 562 are configured to rotate in a direction opposite to that of the spindle gear 564, whereby the opening and closing states of the first shut-off valve 510 and the second shut-off valve 520 can operate in the same manner.

[0177] On the other hand, the third power transmission unit 563 is configured to rotate in the same direction as the spindle gear 564, whereby the bleed valve 540 can operate such that its opening and closing state is opposite to those of the first and second shut-off valves 510, 520.

[0178] The spindle gear 564 may be a cylindrical gear having teeth formed on its outer peripheral surface, for example, a spur gear having a tooth row formed parallel to the axis.

[0179] The first power transmission unit 561 may be provided to mesh with the teeth of the spindle gear 564, and may include a first transmission gear 561-1 that rotates in a direction opposite to that of the spindle gear 564, and a first connection part 561-2 that connects between the first transmission gear 561-1 and the first shut-off valve 510 and opens and closes the first shut-off valve 510 according to the rotational direction of the first transmission gear 561-1.

[0180] The second power transmission unit 562 is provided to mesh with the teeth of the main shaft gear 564, and includes a second transmission gear 562-1 that rotates in the opposite direction to the main shaft gear 564, and a second connection part 562-2 that connects between the second transmission gear 562-1 and the second shut-off valve 520 and opens and closes the second shut-off valve 520 according to the rotation direction of the second transmission gear 562-1.

[0181] The third power transmission unit 563 includes a third transmission gear 563-1 to which the rotational movement of the main shaft gear 564 is directly transmitted and that rotates in the same direction, a fourth transmission gear 563-2 that is provided to mesh with the third transmission gear 563-1 vertically and that rotates in the same direction, and a third connection part 563-3 that connects between the fourth transmission gear 563-2 and the bleed valve 540 and opens and closes the bleed valve 540 according to the rotation direction of the fourth transmission gear 563-2. If the third connection part 563-3 is directly connected to the main shaft gear 564, the configurations of the third transmission gear 563-1 and the fourth transmission gear 563-2 may be omitted.

[0182] Therefore, the rotary actuator 560 of the present embodiment is configured such that the first and second shut-off valves 510, 520 and the bleed valve 540 always operate in opposite states.

[0183] In the present embodiment, it is also possible to use other rotary means instead of the gears 561-1, 562-1, 563-1, 563-2, 564 that constitute the rotary actuator 560.

[0184] As described in the above embodiment, if a system is configured such that the first and second shut-off valves 510 and 520, the check valve 530, and the bleed valve 540 are configured as one valve set, and the valves 510, 520, and 540 that require opening and closing operations are operated at once by one actuator 580 / 560, the control logic becomes simple, the cables and the supply lines of the hydraulic oil are reduced, and as a result, a compact configuration is possible and it becomes easy to install even in a narrow space of a ship. In addition, the number of actuators 580 / 560 for operating the valves is reduced, and cost reduction effects are expected by manufacturing a plurality of valves as one set.

[0185] FIG. 6 is a diagram showing more specifically the internal piping diagram of the backflow prevention valve set according to the present invention. FIG. 7 is a diagram showing the appearance of the backflow prevention valve set according to the present invention. FIG. 8 is a diagram of the backflow prevention valve set shown in FIG. 7 viewed from below.

[0186] FIG. 6 shows more specifically the internal piping diagram of the backflow prevention valve set according to the present invention. Here, the content already described in FIG. 3 shown so as to include only the essential configuration will be omitted from detailed description.

[0187] Referring to FIG. 6, the backflow prevention valve set 500 of one embodiment may include a first flow path 501 that provides a passage for the inflow and discharge of nitrogen gas, and a second flow path 502 that branches from the first flow path 501 and discharges the leakage gas.

[0188] In the backflow prevention valve set 500 of another embodiment, as shown in FIG. 7, since it is integrally formed in one main body B, a flow path through which nitrogen gas and leakage gas flow is formed in the main body B.

[0189] Therefore, it should be understood that the first flow path 501 in this figure constitutes a part of the purge line PL described above, and the second flow path 502 is the same line as the leakage discharge line LL described above. Note that the member numbers are different in FIGS. 3 and 6 so as not to be confused.

[0190] The backflow prevention valve set 500 according to the present invention may further include a filter 504 provided on the most upstream side on the first flow path 501 through which nitrogen gas flows, a manual valve 505 and a pressure sensor 506 sequentially provided between the filter 504 and the first shut-off valve 510, and a sub-check valve 531 provided on the first flow path 501 before the second flow path 502 branches on the downstream side of the first shut-off valve 510.

[0191] The filter 504 serves to prevent foreign matter from being caught in the valves provided downstream by filtering foreign matter contained in the nitrogen gas flowing into the first flow path 501.

[0192] The manual valve 505 functions to physically block the first flow path 501. The manual valve 505 is a valve that can be manually opened and closed, and normally maintains an open state at all times and can be shut off during maintenance.

[0193] The pressure sensor 506 is a sensor that measures the pressure of the nitrogen gas supplied to the first flow path 501, and serves to determine whether the supply of nitrogen gas is good during the purge of the engine system.

[0194] The sub-check valve 531 serves to block again the leakage of LNG gas flowing back from the engine side to the nitrogen supply section side. In the present invention, the sub-check valve 531 is a configuration that supplements the above-described check valve 530 and is not an essential configuration. The sub-check valve 531 can be of a closable type that can be shut off during maintenance, similar to the check valve 530.

[0195] On the other hand, a gas block 507 may be connected to the end of the outlet of the first flow path 501. The gas block 507 functions as a connection for connecting the first flow path 501 to a pipe that requires purging, and is an area where nitrogen gas and the gas flowing back from the engine actually come into contact.

[0196] The "Outer Pipe" shown in FIG. 6 means a pipe for discharging the leaked gas discharged from the second flow path 502 to an external safe area.

[0197] Referring to FIGS. 7 and 8, the backflow prevention valve set 500 according to the present invention has the aforementioned valves 505, 510, 520, 530, 531, 540 and other components 504, 506 integrated in one main body B. That is, the backflow prevention valve set 500 according to the present invention is manufactured as one set.

[0198] Inside the integrated main body B, pipes as shown in FIG. 6 are provided, and valves 505, 510, 520, 540 for opening and closing the pipes provided inside the main body B are provided from the outside, and valves 530, 531 for allowing the fluid flowing through the internal pipes of the main body B to flow only in one direction can be provided from the outside.

[0199] Further, the main body B may be provided with a nitrogen gas inlet 503 for allowing nitrogen gas to flow into the internal first flow path 501 (see FIG. 6), a nitrogen gas outlet 508 for discharging the nitrogen gas flowing into the first flow path 501 (see FIG. 6), and a leakage gas outlet 509 for discharging the leakage gas through the internal second flow path 502.

[0200] A purge line PL extending from the buffer tank 300 (see FIG. 2) can be connected to the nitrogen gas inlet 503, and the aforementioned gas block 507 can be connected to the nitrogen gas outlet 508. Further, an outer pipe (Outer Pipe) shown in FIG. 6 can be connected to the leakage gas outlet 509.

[0201] As described above, the backflow prevention valve set 500 of the present invention in which the first and second shut-off valves 510, 520, the check valve 530 and the bleed valve 540 are integrated has a simplified control logic for backflow prevention, enables a compact configuration of the valve set, thereby not only having an expected effect of cost reduction, but also being easily installed in a narrow space and having an effect of increasing the utilization rate of the ship's internal space.

[0202] Moreover, if the system is configured such that valves 510, 520, and 540 that require opening and closing operations are interlocked and operated by less than three actuators, the cables and the supply lines of the hydraulic oil are reduced, and the above effects are further maximized.

[0203] FIG. 9 is a schematic diagram of a backflow prevention valve set according to the present invention. FIG. 10 is a front view showing the backflow prevention valve set according to the present invention. FIG. 11 is a side view showing the backflow prevention valve set according to the present invention. FIG. 12 is a bottom view showing the backflow prevention valve set according to the present invention.

[0204] Referring to FIG. 9, a backflow prevention valve set 500 according to still another embodiment of the present invention may include a first flow path 501 provided inside to form a flow path for nitrogen gas; an air filter regulator 570, a first shut-off valve 510, a second shut-off valve 520, and a check valve 530 sequentially provided in the first flow path 501; a second flow path 502 branched from the first flow path 501 between the first shut-off valve 510 and the second shut-off valve 520 to discharge leaked gas; a bleed valve 540 provided in the second flow path 502; and a gas block 504 provided at the end of the outlet of the first flow path 501.

[0205] The backflow prevention valve set 500 according to the present invention is integrally formed in one main body B as shown in FIGS. 10 to 12, so that flow paths 501 and 502 through which nitrogen gas and leaked gas flow are formed in the main body B.

[0206] The air filter regulator 570 is provided on the most upstream side of the first flow path 501 to filter foreign substances contained in the inflowing nitrogen gas and to adjust the pressure, speed, flow rate, etc. of the nitrogen gas.

[0207] The gas block 504 serves as a connector for connecting the first flow path 501 to purge lines PL1 and PL2 leading to the engine 100 side, and is an area where nitrogen gas and gas flowing back from the engine actually come into contact.

[0208] In the figure, "Outer Pipe" means a pipe for discharging the leaked gas discharged from the second flow path 502 to an external safe area.

[0209] The first shut-off valve 510 and the second shut-off valve 520 are valves for opening or shutting off the first flow path 501, and can be valves having an opening / closing function such as a ball valve, for example.

[0210] The first shut-off valve 510 and the second shut-off valve 520 are sequentially provided on the upstream side and the downstream side of the first flow path 501, respectively, and always open or shut off simultaneously to doubly shut off or open the flow of nitrogen gas supplied to the first flow path 501.

[0211] The check valve 530 is provided at the most downstream side of the first flow path 501 to prevent the reverse flow of LNG gas from the engine 100 side. The check valve 530 is always in an open state but functions to allow the fluid to flow only in one direction, and thus serves to primarily prevent the reverse flow of LNG gas from the engine 100 side.

[0212] In the present invention, the check valve 530 may be a closable check valve so that it can be shut off during maintenance, or may be manually openable and closable.

[0213] The bleed valve 540 is provided between the first shut-off valve 510 and the second shut-off valve 520, and serves to remove the residual pressure inside when the first shut-off valve 510 and the second shut-off valve 520 are shut off.

[0214] When a leak occurs in the second shut-off valve 520, the leaked gas that has penetrated between the first shut-off valve 510 and the second shut-off valve 520 is discharged to the safe area through the second flow path 502 by opening the bleed valve 540. At this time, since the first shut-off valve 510 blocks the leaked gas again, there is an effect of doubly preventing the reverse flow from the engine 100 side.

[0215] The bleed valve 540 is blocked when the first shut-off valve 510 and the second shut-off valve 520 are opened. That is, the opening and closing operations of the first and second shut-off valves 510, 520 and the bleed valve 540 are always opposite.

[0216] On the other hand, the backflow prevention valve set 500 according to the present invention may further include actuators 511, 521, 541 for opening and closing the first and second shut-off valves 510, 520 and the bleed valve 540. A tube line TL for supplying compressed air (or hydraulic oil) to drive the actuators 511, 521, 541 is connected, and a solenoid valve 550 for controlling the pressure of the supply fluid may be installed on the tube line TL.

[0217] In the figure, three actuators 511, 521, 541 are provided corresponding to the first shut-off valve 510, the second shut-off valve 520, and the bleed valve 540 that require opening and closing operations, respectively. However, the actuators in the present invention may be provided in less than three.

[0218] As described above, the first shut-off valve 510, the second shut-off valve 520, and the bleed valve 540 that require opening and closing operations in the backflow prevention valve set 500 of the present invention have certain characteristics in their opening and closing operations. That is, the first shut-off valve 510 and the second shut-off valve 520 are always opened and closed in the same direction, and the bleed valve 540 is opened and closed in the reverse direction. By utilizing the operating characteristics of these valves 510, 520, 540, two or three valves can be operated at once by one actuator, and thus it is possible to provide less than three actuators.

[0219] Specifically, since the operations of the first and second shut-off valves 510, 520 and the bleed valve 540 are always opposite, a configuration in which they can be operated at once is possible by connecting the first and second shut-off valves 510, 520 and the bleed valve 540 to one actuator with only the direction reversed. Thus, the backflow prevention valve set 500 of the present invention that operates with one actuator can be implemented.

[0220] Further, the first shut-off valve 510 and the second shut-off valve 520 that open and close in the same direction are connected to one actuator, and the bleed valve 540 that opens and closes in the opposite direction is connected to the other actuator, or either the first shut-off valve 510 or the second shut-off valve 520 and the bleed valve 540 are connected to one actuator, and they are interlocked using a mechanical link so that their operations are reversed, and the remaining valve (510 or 520) is connected to the other actuator, whereby the backflow prevention valve set 500 of the present invention that operates with two actuators can be implemented.

[0221] At this time, the actuator is a single acting actuator (also referred to as a "spring return actuator") that shuts off the first and second shut-off valves 510 and 520 with a force such as a spring in an emergency when an electric signal or a fail of compressed air occurs, and the bleed valve 540 is opened, and it can be configured to execute a fail safe function.

[0222] As shown in the figure, when one or more actuators 511, 521, and 541 are provided, one or more tube lines TL connected to the actuators 511, 521, and 541 can also be provided. However, in the present invention, even if there are one or more tube lines TL, it is preferable that only one solenoid valve 550 is provided on an integrated line. Although the solenoid valve 550 is not configured to handle gas, when it is arranged in the gas valve unit room, an expensive explosion-proof device needs to be applied because it is an electrical component, so it is more cost-effective to reduce the number.

[0223] The solenoid valve 550 can be arranged in the gas valve unit room together with the backflow prevention valve set 500, and in the present invention, by providing at least less than 3 (most preferably 1) solenoid valves 550 as described above, the cost for designing expensive explosion-proof equipment can be reduced.

[0224] Also, as shown in FIG. 2, a solenoid valve group 600 equipped with a solenoid valve 550 is positioned inside the engine room (gas safety area) at a position closest to the wall side partitioning the gas valve unit room and the engine room, and only the tube lines TL connected from the solenoid valve group 600 to the actuators 511, 521, 541 are extended through to the gas valve unit room so that a general solenoid valve can be applied.

[0225] According to the configuration of the present invention as described above, by minimizing the number of solenoid valves 550 to which an expensive explosion-proof device is applied to one, or by arranging the solenoid valve group 600 inside the engine room which is a gas safety area, the application of an expensive explosion-proof device becomes unnecessary, and a very advantageous design in terms of cost becomes possible. Incidentally, as will be described later, in the present invention, the solenoid valve 550 is designed to be included in an integrated configuration with the backflow prevention valve set 500 and can be easily installed on the ship.

[0226] In FIGS. 10 to 12, the external structure of the backflow prevention valve set 500 according to the present invention is shown more specifically. Referring to FIGS. 10 to 12, it can be seen that the backflow prevention valve set 500 according to the present invention integrates the aforementioned valves 510, 520, 530, 540 and other components 570, 504 with one body B. That is, the backflow prevention valve set 500 according to the present invention can be configured and manufactured as one set.

[0227] Although not shown, flow paths 501 and 502 as shown in FIG. 9 may be formed to penetrate the main body B constituting the main body of the backflow prevention valve set 500, and valves 510, 520, and 540 for opening and closing the flow paths 501 and 502 formed inside, and a check valve 530 for allowing fluid to flow in only one direction may be provided controllably outside the main body B. Specifically, the first and second shut-off valves 510 and 520 and the check valve 530 are provided on the side portion of the main body B, and the bleed valve 540 is provided at the upper end portion of the main body B, and each can be installed so as to penetrate from the outside of the main body B and open and close the flow paths 501 and 502 formed inside the main body B.

[0228] In addition, on the outer portion of the main body B, a nitrogen gas inlet 503 for allowing nitrogen gas to flow into the first flow path 501 formed inside, a nitrogen gas outlet 508 for discharging the introduced nitrogen gas, and a leakage gas outlet 509 through which leakage gas is discharged via the second flow path 502 formed inside can be formed. The spool piece forming the nitrogen gas inlet 503 and the nitrogen gas outlet 508 can be fixed to the outside of the main body B by an eye bolt. A purge line PL extending from the buffer tank 300 (see FIG. 2) is connected to the nitrogen gas inlet 503, and the aforementioned gas block 507 can be provided in a connector form at the nitrogen gas outlet 508 to connect the fading lines PL1 and PL2 connected by the engine. And an outer pipe shown in FIG. 9 can be connected to the leakage gas outlet 509.

[0229] On the bottom surface portion of the main body B, a bracket 590 for installing the air filter regulator 570 and the solenoid valve 550 may be provided. The bracket 590 may have a form that is fixed at the lower end portion of the side surface of the main body B and then bent to be horizontal with the bottom surface of the main body B. The air filter regulator 570 can penetrate onto the first flow path 501 from the outside of the main body B. As described above, only one solenoid valve 550 of the present invention can be configured.

[0230] In addition, the main body B can be configured so that other sensors such as a pressure sensor can be additionally mounted.

[0231] As described above, the backflow prevention valve set 500 of the present invention in which various valves 510, 520, 540, 550 and other components 570, 504, 503, 508, 509, 508 are integrally formed in the body B has a compact configuration and can be easily arranged in a narrow space such as a gas valve unit room. Therefore, it has the effect of increasing the utilization rate of the space inside the ship.

[0232] Further, the backflow prevention valve set 500 according to the present invention minimizes the configuration that applies an expensive explosion-proof device, and by an optimal design such as interlocking valves 510, 520, 540 that require opening and closing operations via less than three actuators, it achieves the effect of reducing the amount of materials and the effect of simplifying the backflow prevention control logic.

[0233] On the other hand, the backflow prevention valve set 500 proposed in the present invention is not limited to being applied only to the gas purge system of the present invention shown in FIG. 2, but can be applied to all systems in which a purge line is directly connected to a pipe through which liquefied gas supplied as fuel for the engine flows, and of course, it can also be applied when injecting nitrogen gas onto the fuel supply line as in the prior art. Further, the backflow prevention valve set 500 of the present invention can be applied not only to the gas purge system but also to other gas treatment systems where there is a risk of fluid backflow.

[0234] The backflow prevention valve set 500 according to the present invention described above can be operated in two concepts as follows for the high-pressure gas injection engine 110 side and the low-pressure gas injection engine 120 side, respectively. Here, since the operations of the first backflow prevention valve set 500A provided in the first purge line PL1 connected to the high-pressure gas injection engine 110 side and the second backflow prevention valve set 500B provided in the second purge line PL2 connected to the low-pressure gas injection engine 120 side may be different from each other, each case will be described.

[0235] 1) Operating Characteristics of the First Backflow Prevention Valve Set 500A When the high-pressure gas injection engine 110 is in normal gas operation, the first shut-off valve 510 and the second shut-off valve 520 in the first backflow prevention valve set 500A maintain the shut-off (Normal Close) state, and the bleed valve 540 is opened (Normal Open). When fuel gas leaks, the leaked gas is discharged to a safe area through the second flow path 502. Here, "normal gas operation" means the operating state of the "gas mode" in which the engine is driven using LNG gas as fuel.

[0236] During purging of the high-pressure gas injection engine 110, the first and second shut-off valves 510 and 520 of the first backflow prevention valve set 500A are opened, and nitrogen gas is supplied from the buffer tank 300 to the high-pressure gas injection engine 110 for purging.

[0237] On the other hand, the gas purging system of the ship according to the present invention may include a third purge line PL3 that branches from the rear end of the first backflow prevention valve set 500A in the first purge line PL1 and is connected to the second fuel supply line L2. An openable and closable purge valve PV3 may be provided on the third purge line PL3.

[0238] The nitrogen gas supplied through the third purge line PL3 purges the second fuel supply line L2 from the rear end of the master valve MV provided on the second fuel supply line L2 and responsible for supplying fuel (LNG gas) to the low-pressure gas injection engine 120 to the low-pressure gas valve unit 220, and then is discharged through the vent line VL2 connected to the low-pressure gas valve unit 220.

[0239] Thus, the purging performed through the third purge line PL3 is referred to as Manual Purging to distinguish it from Auto Purging. Auto Purging is to automatically purge when the engines trip in cooperation with the gas trips of the engines 110 and 120, which means purging between the gas valve units 210 and 220 and the engines 110 and 120. The Manual Purging through the third purge line PL3 in the present invention can be performed by pressing an operation button during maintenance of the low-pressure gas injection engine 120 or when the gas mode is not used for a long time.

[0240] Thus, the first check valve set 500A provided on the high-pressure gas injection engine 110 side in the present invention can be configured in cooperation with the manual purge system, thereby expecting the effect of reducing the amount of substances.

[0241] 2) Operating characteristics of the second check valve set 500B Before explaining the operating characteristics of the second check valve set 500B provided on the low-pressure gas injection engine 120 side, a nitrogen supply valve NV and a check valve CV may be provided on the second purge line PL2 between the second check valve set 500B and the low-pressure gas injection engine 120 in the present invention.

[0242] The nitrogen supply valve NV is a valve that is opened during purging of the low-pressure gas injection engine 120 and maintains a closed state during normal times. And the check valve CV is a valve that prevents backflow at the connection part between the purge line PL and the low-pressure gas injection engine 120.

[0243] That is, on the low-pressure gas injection engine 120 side, the nitrogen supply valve NV and the check valve CV provided between the second check valve set 500B and the low-pressure gas injection engine 120 prevent backflow of the fuel gas from the low-pressure gas injection engine 120 preemptively.

[0244] A first pressure sensor PT1 may be provided at the front end of the nitrogen supply valve NV. The first pressure sensor PT1 detects whether the pressure of the nitrogen gas supplied through the second purge line PL2 is normal, and when the pressure of the nitrogen gas drops below a predetermined pressure (for example, about 7 bar), controls the low-pressure gas injection engine 120 not to operate in the gas mode any further.

[0245] Also, a second pressure sensor PT2 may be provided between the nitrogen supply valve NV and the check valve CV. The second pressure sensor PT2 can detect an increase in pressure when fuel gas flows back from the low-pressure gas injection engine 120 and issue an instruction to stop the gas mode operation of the low-pressure gas injection engine 120.

[0246] Next, looking at the operating characteristics of the second backflow prevention valve set 500B, when the low-pressure gas injection engine 120 is operating in normal gas mode, the first shut-off valve 510 and the second shut-off valve 520 of the second backflow prevention valve set 500B are opened (Normally Open) to sufficiently provide the pressure of the nitrogen gas through the purge line PL2. At this time, the bleed valve 540 is shut off (Normally Close). In this way, if a system is configured in which the nitrogen gas is pressurized up to the front end of the low-pressure gas injection engine 120, there is an advantage that the response speed is increased.

[0247] At this time, when the pressure of the nitrogen gas detected by the first pressure sensor PT1 provided at the front end of the nitrogen supply valve NV drops below a predetermined pressure (for example, about 7 bar), the first and second shut-off valves 510 and 520 of the second backflow prevention valve set 500B are shut off, and the bleed valve 540 is controlled to open. When the pressure of the nitrogen gas becomes low, it is determined that the pressure of the fuel gas becomes higher than the pressure of the nitrogen gas and the possibility of backflow is high. Therefore, the second backflow prevention valve set 500B side is also controlled so that the backflow prevention function can be executed. Here, even when the first and second shut-off valves 510 and 520 are shut off, the nitrogen supply valve NV can maintain the shut-off state. The nitrogen supply valve NV is controlled according to whether or not purging is performed by the gas trip signal of the low-pressure gas injection engine 120.

[0248] Also, when a backflow from the low-pressure gas injection engine 120 is detected by the second pressure sensor PT2 provided between the nitrogen supply valve NV and the check valve CV, the first and second shut-off valves 510 and 520 of the second backflow prevention valve set 500B are similarly shut off, and the bleed valve 540 is controlled to open. At this time, if a backflow from the low-pressure gas injection engine 120 is detected, the gas mode operation of the low-pressure gas injection engine 120 must be stopped. However, by preventing the backflow with the second backflow prevention valve set 500B, the gas mode operation of the low-pressure gas injection engine 120 can be maintained for a short period of time.

[0249] During purging of the low-pressure gas injection engine 120, all of the nitrogen supply valve NV and the first and second shut-off valves 510 and 520 of the second backflow prevention valve set 500B are opened to supply nitrogen gas from the buffer tank 300 to the low-pressure gas injection engine 120 side.

[0250] On the other hand, the second backflow prevention valve set 500B provided on the low-pressure gas injection engine 120 side in the present invention is not configured in cooperation with the manual purge system because the first and second shut-off valves 510 and 520 are in the normal open state.

[0251] FIG. 13 is a configuration diagram of a nitrogen supply system for a dual fuel engine according to an embodiment of the present invention.

[0252] Referring to FIG. 13, the nitrogen supply system for a dual fuel engine according to the present invention can be driven using fuel gas, and includes an engine unit 1000 provided in a propulsion engine of a ship, a fuel supply system 4000 that supplies the fuel gas according to the conditions of the engine unit 1000, a low-pressure gas valve unit 2200 that controls the pressure and flow rate of the fuel gas supplied to the engine unit 1000, a nitrogen supply unit that supplies nitrogen for purging the inside of the engine unit 1000, and an outside air discharge unit that discharges residual gas inside the engine unit 1000 to a safe area according to the nitrogen supply.

[0253] The engine unit 1000 includes an engine that can be driven using LNG (Liquefied Natural Gas) as fuel, and specifically, it can be a DF engine (Duel Fuel engine). The DF engine is an engine that uses dual fuels and is a kind of hybrid concept engine that can use natural gas and heavy oil (such as diesel) simultaneously. For example, in the case of the DF engine, when high load is required such as when starting the engine, marine diesel fuel can be used to increase the engine output, and during operation, gas fuel can be used for operation.

[0254] Also, the engine unit 1000 includes a low-pressure gas injection engine that is driven by being supplied with LNG gas compressed at low pressure, and is driven by being supplied with LNG gas compressed and vaporized at less than 10 Bar. For example, a general generator engine such as DFDG (Dual Fuel Diesel Generator) (DFGE: Duel Fuel Generator Engine) or a propulsion engine such as X-DF (eXtreme Dual Fuel) can be applied.

[0255] Also, the engine unit 1000 is provided with one or more engines, including a first engine 1100 and a second engine 1200, and the first engine 1100 and the second engine 1200 are preferably arranged in an engine room (Engine Room, E / R).

[0256] The engine room is classified as a gas safe zone, which is an area that requires safety from the gas hazardous zone. For example, direct entry and exit from the gas hazardous zone to the gas safe zone are prohibited (install an Air Lock if necessary), and the fuel supply line (fuel supply pipe) passing through the gas safe zone must be completely enclosed by a double pipe or duct.

[0257] The fuel supply system 4000 is provided in the cargo compressor room and is equipped with a fuel storage tank (not shown) for storing fuel gas (LNG) to be supplied to the first engine 1100 and the second engine 1200. The fuel gas stored in the fuel storage tank is compressed and vaporized by the fuel supply system (Gas supply system) and supplied as fuel for the first engine 1100 and the second engine 1200.

[0258] Specifically, it is supplied to the first engine 1100 and the second engine 1200 via the main fuel supply line connected to the fuel supply system 4000, and a master gas valve for adjusting the supply of the fuel gas may be provided in the main fuel supply line.

[0259] Also, the main fuel supply line branches from within the gas valve unit room (GVU room: Gas Valve Unit Room) into a first fuel supply line L1 and a second fuel supply line L2. The first fuel supply line is connected to the first engine 1100, and the second fuel supply line L2 is connected to the second engine 1200.

[0260] At this time, the first fuel supply line L1 connecting from the gas valve unit room to the first engine 1100 and the second fuel supply line L2 connecting to the second engine 1200 are preferably formed of a double pipe.

[0261] The gas valve unit room is a space classified as a gas hazardous area and must be arranged in a separate area from the engine room (E / R). Furthermore, periodic ventilation is required for safety, and it is necessary to be prepared for gas leakage by enabling the replacement of normal dry air 30 times per hour. Therefore, the gas valve unit room is provided with an outside air discharge part for discharging gas to the outside.

[0262] Specifically, an exhaust fan may be provided for ventilation, and a gas detection sensor for detecting the occurrence of gas leakage may be provided at the front end of the exhaust fan.

[0263] The low-pressure gas valve unit 2200 is a device that groups valves for controlling the pressure and flow rate of fuel gas supplied to the engine unit (the first engine 1100 and the second engine 1200), and can be provided between the engine unit 1000 and the fuel supply system 4000.

[0264] Specifically, the low-pressure gas valve unit 2200 is arranged on the main fuel supply line, and it is preferable that the low-pressure gas valve unit 2200 be arranged in a gas valve unit room.

[0265] Further, the low-pressure gas valve unit 2200 includes a first low-pressure gas unit 2210 and a second low-pressure gas unit 2220. It is preferable to arrange the first low-pressure gas unit 2210 on the first fuel supply line L1 and the second low-pressure gas unit 2220 on the second fuel supply line L2.

[0266] The first low-pressure gas unit 2210 and the second low-pressure gas unit 2220 are provided with first pipe purge valves 2214, 2224, second pipe purge valves 2215, 2225, engine purge valves 2216, 2226, pressure regulating valves 2211, 2221, first shut-off valves 2212, 2222, and second shut-off valves 2213, 2223.

[0267] Specifically, the first pipe purge valves are arranged between the pressure regulating valves 2211, 2221 and the first shut-off valves 2212, 2222. The second pipe purge valves 2215, 2225 are arranged between the first shut-off valves 2212, 2222 and the second shut-off valves 2213, 2223. The engine purge valves 2216, 2226 are arranged at the rear ends of the second shut-off valves 2213, 2223.

[0268] That is, the first shut-off valves 2212 and 2222 and the second shut-off valves 2213 and 2223 are arranged at regular intervals in the fuel supply lines (the first fuel supply line L1 and the second fuel supply line L2) to which fuel is supplied, and can be purged at regular intervals.

[0269] At this time, purging means removing the fuel gas remaining in the line for supplying fuel to the engine and the engine system when the engine is not operated for a long time or when the inside of the engine system is to be maintained.

[0270] The nitrogen supply unit may further include a nitrogen buffer tank 3000 for storing nitrogen to use nitrogen as a purge gas, a nitrogen buffer tank pressure sensor 3100 for measuring the pressure of the nitrogen buffer tank 3000, and a nitrogen supply adjustment unit 330 (N2 DBB: N2 Double block & bleed valve + Closable Valve) for adjusting the supply of nitrogen to the engine unit 1000.

[0271] The backflow prevention valve set 5000 is preferably in an always-open state when the engine unit 1000 is operating in gas mode and in a closed state when in diesel mode.

[0272] Specifically, the nitrogen buffer tank 3000 is provided inside the engine room, the backflow prevention valve set 5000 is provided in the gas valve unit room, the nitrogen buffer tank 3000 and the backflow prevention valve set 5000 are connected to the first nitrogen supply line, and the backflow prevention valve set 5000 and the engine unit 1000 are connected to the second nitrogen supply line.

[0273] At this time, the second nitrogen supply line branches inside the engine room and is connected to the first engine 1100 and the second engine 1200 respectively. That is, one backflow prevention valve set 5000 can be applied to a plurality of engines.

[0274] On the one hand, the backflow prevention valve set 5000 serves to supply nitrogen gas for nitrogen purging and prevent the backflow of fuel gas from the engine unit 1000, and is composed of a valve group including a first nitrogen shut-off valve 5100, a second nitrogen shut-off valve 5200, a first nitrogen supply valve 5300, and a first backflow prevention valve 5500.

[0275] The first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200 shut off the nitrogen supply when leakage is detected, and can be valves having an opening and closing function such as a ball valve.

[0276] At this time, the first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200 are provided sequentially and can always be opened or shut off simultaneously to doubly shut off or open the flow of nitrogen gas supplied to the second nitrogen supply line.

[0277] The first nitrogen supply valve 5300 adjusts the nitrogen supply to the engine unit 1000, and a check valve having a function of allowing the fluid to flow in only one direction can be arranged. By arranging the first nitrogen supply valve 5300 as a check valve, the backflow of fuel gas from the engine unit 1000 can be prevented.

[0278] Also, the first nitrogen supply valve 5300 may be a closable check valve so that it can be shut off during maintenance, and may be manually openable and closable.

[0279] The first backflow prevention valve 5500 is provided between the first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200 by arranging a bleed valve.

[0280] The first check valve 5500 discharges the fuel gas to the outside, prevents backflow into the nitrogen supply line, and removes the residual pressure inside when the first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200 are closed (shut off).

[0281] When a leak occurs in the second nitrogen shut-off valve 5200, the leaked gas between the first nitrogen shut-off valve 5100 and the second shut-off valve 332 opens the first check valve 5500 and is discharged to a safe area. At this time, since the first nitrogen shut-off valve 5100 blocks the leaked gas again, there is an effect of doubly preventing backflow from the engine unit 1000.

[0282] That is, the first check valve 5500 closes (shuts off) when the first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200 are opened, and the opening and closing operations of the first check valve 5500 are opposite to those of the first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200.

[0283] On the other hand, the check valve set 5000 may further include an actuator (not shown) for opening and closing the first nitrogen shut-off valve 5100, the second nitrogen shut-off valve 5200, and the first check valve 5500.

[0284] The actuator can be configured to execute a fail-safe function by providing a single-acting actuator (also referred to as a "spring return actuator") that closes the first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200 with a force such as a spring and opens the first check valve 5500 in the event of an emergency where an electrical signal or a fail of compressed air occurs.

[0285] The engine unit 1000 includes second nitrogen supply valves 5610 and 5620, first pressure sensors 5810 and 5820, second backflow prevention valves 5710 and 5720, and second pressure sensors 5910 and 5920 provided on the second nitrogen supply line.

[0286] The second nitrogen supply valves 5610 and 5620 are opened upon receiving a signal when nitrogen supply to the inside of the engine unit is necessary, maintain a closed state (closed condition) during normal times, and are opened when purging is carried out.

[0287] The second backflow prevention valves 5710 and 5720 prevent backflow of fuel gas at the connection site between the second nitrogen supply line and the engine unit 1000, and a check valve can be arranged.

[0288] That is, in the engine unit 1000, backflow of fuel gas from the engine unit 1000 is preemptively prevented by the second nitrogen supply valves 5610 and 5620 and the second backflow prevention valves 5710 and 5720.

[0289] The first pressure sensors 5810 and 5820 are provided at the front ends of the second nitrogen supply valves 5610 and 5620, and the first pressure sensors 5810 and 5820 detect whether the nitrogen gas supplied via the second nitrogen supply line is normal.

[0290] Also, the second pressure sensors 5910 and 5920 are provided between the second nitrogen supply valves 5610 and 5620 and the second backflow prevention valves 5710 and 5720, and detect an increase in pressure when fuel gas backflows from the engine unit 1000.

[0291] On the other hand, the nitrogen supply system of the dual fuel engine according to the present invention further includes a control unit 7000. The control unit 7000 controls the opening and closing of valves in the system based on the measured pressure, and controls the operation and purging of the system.

[0292] Hereinafter, with reference to the nitrogen supply system of the dual fuel engine according to the above-described embodiment of the present invention, a control method of the nitrogen supply system of the dual fuel engine according to an embodiment of the present invention will be described.

[0293] In the nitrogen supply control method of the nitrogen supply system of the dual fuel engine, the method includes a step of controlling the supply of fuel gas from the fuel supply system 4000 to the engine unit 1000 and a step of controlling the opening and closing of the nitrogen supply adjustment unit according to the supply of the fuel gas.

[0294] The step of controlling the supply of the fuel gas controls to supply fuel gas from the fuel supply system 4000 to the engine unit 1000 when the engine unit 1000 is in normal gas operation and to stop the supply of fuel gas when the normal gas operation stops.

[0295] Specifically, during normal gas operation, fuel gas is supplied to the low-pressure gas valve unit 2200 through the main fuel gas line connected to the fuel supply system 4000, and fuel is supplied from the low-pressure gas valve unit 2200 to the first engine 1100 through the first fuel supply line L1 and to the second engine 1200 through the second fuel supply line L2, and the supply of fuel gas is stopped when the normal gas operation stops.

[0296] Here, the normal gas operation means an operation state in a gas mode in which the first engine 1100 and the second engine 1200 included in the engine unit 1000 are driven using LNG gas as fuel.

[0297] The step of controlling the opening and closing of the backflow prevention valve set 5000 includes a step of opening the backflow prevention valve set 5000 and a step of closing it.

[0298] The step of opening is to open the check valve set 5000 during the supply of the fuel gas to supply nitrogen gas, and to control the opening of the first nitrogen shut-off valve 5100, the second nitrogen shut-off valve 5200 and the first nitrogen supply valve 5300 of the check valve set 5000, and the closing of the second nitrogen supply valves 5610, 5620 and the second check valves 5710, 5720.

[0299] That is, the engine unit 1000 is supplied with fuel gas and operates in gas mode, and the nitrogen gas maintains a pressurized state up to the front end of the engine unit 1000.

[0300] By configuring such a system, the response speed can be increased to perform a rapid purge, and it operates so that a rapid vent can be performed when a reverse flow of fuel gas occurs.

[0301] The step of opening further includes measuring pressure, and measuring pressure with the first pressure sensors 5810, 5820 and the second pressure sensors 5910, 5920.

[0302] When the pressure of the first pressure sensors 5810, 5820 becomes lower than a predetermined pressure, the fuel gas in the engine unit 1000 can flow backward, the supply of the fuel gas is stopped, the gas mode of the engine unit 1000 is stopped, and a purge is urgently performed with the engine scavenging air.

[0303] Also, when the pressure of the second pressure sensors 5910, 5920 rises, it is determined that fuel gas has flowed backward from the engine unit 1000, the supply of the fuel gas is stopped, the gas mode of the engine unit 1000 is stopped, and a purge is urgently performed with the scavenging air of the engine.

[0304] Specifically, the first nitrogen shut-off valve 5100 and the second nitrogen shut-off valve 5200 of the check valve set 5000 are closed, and the first check valve 5500 and the second nitrogen supply valves 5610, 5620 are opened to discharge the fuel gas to a safe area of the outside air discharge part.

[0305] Furthermore, the step of opening further includes a purging step of stopping the supply of fuel gas and purging with nitrogen.

[0306] This is to normally stop the gas mode of the engine unit 1000 and perform purging with nitrogen, and purging can be quickly performed using nitrogen gas that is already in a pressurized state.

[0307] Specifically, the purging step can be carried out in three ways, and it is preferable to select and carry out according to the section where purging is performed.

[0308] First, in the purging step, the second nitrogen supply valves 5610, 5620 and the engine purge valves 2216, 2226 are opened, and the first shut-off valves 2212, 2222 and the second shut-off valves 2213, 2223 are closed, so that the fuel gas in the engine unit 1000, the first fuel supply line L1 and the second fuel supply line L2 is purged with the nitrogen supplied to the engine unit 1000 side and discharged to a safe area.

[0309] Second, in the purging step, the second nitrogen supply valves 5610, 5620, the engine purge valves 2216, 2226, and the second shut-off valves 2213, 2223 are opened, and the first shut-off valves 2212, 2222 are closed to perform purging. At this time, when performing purging by opening the second shut-off valves 2213, 2223, it is necessary to simultaneously open the second pipe purge valves 315, 325 to perform purging.

[0310] That is, in the purging step, it is necessary to always keep the first shut-off valves 312, 322 closed, and it is preferable to control the opening and closing of the second shut-off valves 2213, 2223, the second pipe purge valves 315, 325, and the engine purge valves 2216, 2226 according to the purging section.

[0311] Thirdly, the purging step can perform a manual purging. The manual purging is preferably performed when the gas operation has not been carried out for a long time in the engine unit 1000 or maintenance is required.

[0312] Specifically, a nitrogen supply line (not shown) is further provided at the rear end of the master gas valve, and the nitrogen supply line (not shown) is connected to the first low-pressure gas unit 2210 and the second low-pressure gas unit 2220 respectively.

[0313] At this time, when the manual purging is performed, nitrogen is supplied to the nitrogen supply line (not shown), and the fuel gas is discharged to the external safety area through the first pipe purge valves 2214 and 2224.

[0314] The closing step closes the check valve set 5000 to stop the nitrogen supply when the pressures of the second pressure sensors 5910 and 5920 are higher than those of the first pressure sensors 5810 and 5820, or when the pressure of the nitrogen buffer tank 3000 is 5 Bar or less.

[0315] At this time, the closing step is performed when the following conditions are simultaneously satisfied.

[0316] First, it is performed when the engine unit 1000 is in operation in gas mode.

[0317] Second, it is performed when all of the first shut-off valves 2212 and 2222 and the second shut-off valves 2213 and 2223 of the low-pressure gas valve unit 2200 are opened.

[0318] For example, even when the engine unit 1000 is in operation in gas mode, a leakage test or a purge at the initial stage of operation can be performed. However, in the above cases, the first shut-off valves 2212 and 2222 and the second shut-off valves 2213 and 2223 are not opened simultaneously.

[0319] Therefore, it is determined that the supply of fuel gas to the engine unit 1000 is normal only when the first shut-off valves 2212 and 2222 and the second shut-off valves 2213 and 2223 are opened simultaneously. Since fuel gas backflow may occur only in this case, the step of closing the backflow prevention valve set 5000 is executed.

[0320] Thirdly, a predetermined time after the backflow prevention valve set 5000 is opened is regarded as the preparation time for fuel gas, and the step of closing the backflow prevention valve set 5000 is executed.

[0321] With the above configuration, it is possible to apply only one backflow prevention valve set 5000 to a plurality of engines. When fuel gas backflow occurs in any one of the engines, the backflow prevention valve set 5000 is closed to stop the gas mode operation of the engine unit 1000 and close the master gas valve.

[0322] At this time, if no leakage is detected by the second pressure sensors 5910 and 5920, or if the pressure of the second pressure sensors 5910 and 5920 is lower than that of the first pressure sensors 5810 and 5820, the engine unit 1000 can be temporarily operated in the gas mode.

[0323] As described above, unlike the conventional method of injecting nitrogen gas onto the fuel supply line to purge the inside of the engine system, the present invention directly supplies nitrogen gas to the engine unit 1000 side, so that the residual gas inside the engine system is purged from the engine unit 1000 to the low-pressure gas valve unit 2200 side.

[0324] In addition, since nitrogen gas is directly supplied from the nitrogen buffer tank 3000 to the engine unit 1000, and the residual gas inside the engine units 100 and 110 is discharged through the low-pressure gas valve unit 2200, there is no need to additionally install a belt pipe inside the engine room, and the YARD amount can be reduced compared to the conventional method.

[0325] In addition, in the present invention, since the pipe through which residual gas is purged and discharged from the engine unit 1000 is arranged in the gas valve unit room (GVU room), the gas pipes arranged inside the engine room can be significantly reduced, and there is an effect of maximizing stability.

[0326] In addition, since there are many electrical equipment, devices handling oils, ignition devices, etc. in the engine room, stability is maximized by arranging the gas pipes to a minimum inside the engine room as in the present invention.

[0327] In addition, the gas valve unit room (GVU room) is designed on the assumption that there is a possibility of gas leakage, so air exchange is constantly carried out 30 times per hour, and it is very advantageous for ventilation to use this area to discharge the residual gas of the engine system.

[0328] In addition, when purging is carried out from the engine units 100 and 110 to the low-pressure gas valve unit 2200 side, the residual gas is discharged into the first fuel supply line L1 and the second fuel supply line L2 composed of double pipes. Therefore, the utilization rate of existing equipment is increased, and there is no need to additionally install double pipes for discharging residual gas, which is also preferable in terms of cost.

[0329] In addition, nitrogen gas can always purge the engine unit very quickly while being pressurized, preventing the backflow of fuel gas.

[0330] In addition, even if backflow occurs, the nitrogen supply adjustment unit is quickly shut off to prevent the backflow of fuel gas into the nitrogen buffer tank, and the fuel gas is quickly discharged to the safe area by the first backflow prevention valve 5500.

[0331] In addition, since one backflow prevention valve set 5000 is applied to a plurality of engines, the volume occupied on the ship can be reduced.

[0332] The above description has illustratively explained the technical idea of the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications, changes, and substitutions without departing from the essential characteristics of the present invention. Therefore, the embodiments and the attached drawings disclosed in the present invention are for the purpose of explanation rather than for limiting the technical idea of the present invention, and the scope of the technical idea of the present invention is not limited by such embodiments and the attached drawings. The protection scope of the present invention should be interpreted according to the following claims, and all technical ideas within the equivalent scope must be construed as being included in the scope of rights of the present invention.

Claims

1. An engine section driven by fuel gas and provided as a propulsion engine for a ship; and a fuel supply system for supplying fuel gas to the engine section in response to a condition of the engine section; and A low-pressure gas valve unit that controls the pressure and flow rate of fuel gas supplied to the engine unit; and A nitrogen supply unit that supplies nitrogen gas to purge the inside of the engine unit; and and an outside air exhaust section that exhausts residual gas inside the engine section to a safety area in response to the supply of nitrogen gas.

2. The fuel supply system and the engine are connected via a main fuel supply line, 2. The nitrogen supply system of a dual fuel engine as claimed in claim 1, wherein the main fuel supply line branches into the first fuel supply line and the second fuel supply line in the gas valve unit room.

3. a low-pressure gas valve unit is disposed in the main fuel supply line; the low-pressure gas valve unit portion includes a first low-pressure gas valve unit portion and a second low-pressure gas valve unit portion, 3. The nitrogen supply system of a dual fuel engine as claimed in claim 2, characterized in that the first low pressure gas valve unit portion and the second low pressure gas valve unit portion are arranged in the gas valve unit room, the first low pressure gas valve unit portion is arranged in the first fuel supply line, and the second low pressure gas valve unit portion is arranged in the second fuel supply line.

4. the low pressure gas valve unit includes a first piping purge valve, a second piping purge valve, an engine purge valve, a pressure regulating valve, a first shutoff valve, and a second shutoff valve; The first piping purge valve is disposed between the pressure regulating valve and the first shutoff valve; The second piping purge valve is disposed between the first shutoff valve and the second shutoff valve; 2. A nitrogen supply system for a dual fuel engine according to claim 1, characterized in that the engine purge valve is located downstream of the second shutoff valve.

5. The nitrogen supply unit further includes a nitrogen supply adjustment unit that adjusts the supply of nitrogen gas to the engine unit; the nitrogen supply adjustment unit is connected to the nitrogen supply unit via a first nitrogen supply line and is disposed in the gas valve unit room; 2. The nitrogen supply system of a dual fuel engine according to claim 1, characterized in that the engine part is connected to the nitrogen supply adjustment part via a second nitrogen supply line.

6. The nitrogen supply adjustment unit is a first nitrogen shutoff valve and a second nitrogen shutoff valve that shut off the supply of nitrogen gas when a leak is detected in the second nitrogen supply line; and a first nitrogen supply valve for adjusting the supply of nitrogen gas to the engine; and 6. The nitrogen supply system of a dual fuel engine as claimed in claim 5, further comprising: a first check valve for discharging the fuel gas to the outside of the gas valve unit room and preventing backflow into the first nitrogen supply line.

7. The engine unit includes: a second nitrogen supply valve disposed in the second nitrogen supply line and opened in response to a signal when it is necessary to supply nitrogen gas to the inside of the engine; and a first pressure sensor disposed on the second nitrogen supply line upstream of the second nitrogen supply valve; and a second check valve for preventing backflow of the fuel gas into the second nitrogen supply line; and 6. The nitrogen supply system of a dual fuel engine according to claim 5, further comprising: a second pressure sensor disposed between the second nitrogen supply valve and the second check valve.

8. A nitrogen supply control method for a nitrogen supply system of a dual fuel engine, comprising: The nitrogen supply system controls the supply of fuel gas from the fuel supply system to the engine section; and and controlling the opening and closing of the nitrogen supply adjusting unit in response to the supply of fuel gas; 11. A method for controlling a nitrogen supply system of a dual-fuel engine, wherein the step of controlling the opening and closing of a nitrogen supply adjustment unit includes the steps of opening the nitrogen supply adjustment unit and closing the nitrogen supply adjustment unit.

9. The step of opening the nitrogen supply adjustment unit includes supplying a fuel gas and a nitrogen gas, 9. The method for controlling a nitrogen supply system of a dual fuel engine as claimed in claim 8, characterized in that the first nitrogen shutoff valve, the second nitrogen shutoff valve and the first nitrogen supply valve of the nitrogen supply adjusting unit are opened, and the first check valve and the second nitrogen supply valve are closed.

10. The step of opening the nitrogen supply regulator further includes the step of measuring a pressure with a second pressure sensor; When the pressure measured by the second pressure sensor increases, it is determined that the fuel gas has flowed back, and the supply of the fuel gas is stopped.

10. The method for controlling a nitrogen supply system of a dual fuel engine as claimed in claim 9, further comprising: closing the first nitrogen shutoff valve and the second nitrogen shutoff valve, and opening the first check valve and the second nitrogen supply valve to discharge fuel gas to a safety area.

11. The step of opening the nitrogen supply adjustment unit further includes a nitrogen purging step of stopping the supply of the fuel gas and purging the nitrogen gas; The nitrogen purge step is 9. The method of claim 8, further comprising the steps of: opening the second nitrogen supply valve and the engine purge valve, and closing the first and second shutoff valves to purge the engine section, the first and second fuel supply lines.

12. The step of opening the nitrogen supply adjustment unit further includes a nitrogen purging step of stopping the supply of the fuel gas and purging the nitrogen gas; The nitrogen purge step comprises:

9. The method for controlling a nitrogen supply system of a dual fuel engine as claimed in claim 8, further comprising: opening the second nitrogen supply valve, the second shutoff valve and the engine purge valve, and closing the first shutoff valve to purge the engine section, the first fuel supply line and the second fuel supply line.

13. The step of closing the nitrogen supply adjustment unit includes:

9. The method for controlling a nitrogen supply system of a dual fuel engine according to claim 8, characterized in that, when the pressure measured by the second pressure sensor is higher than the pressure measured by the first pressure sensor or when the pressure of the nitrogen supply unit is below 5 Bar, the nitrogen supply adjustment unit is closed to stop the supply of nitrogen gas.

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