KR20220139754A - fuel supply system - Google Patents

Abstract

The present invention relates to a fuel supply system, which supplies fuel to an engine running in a gas mode of consuming gas fuel or an oil mode of consuming oil fuel. The engine allows gas fuel or oil fuel to be supplied through one injector, allows surplus gas fuel or surplus oil fuel to be recovered through one outlet, and includes: a gas fuel supply unit having a gas fuel supply line connected to the injector and for supplying gas fuel to the engine; an oil fuel supply unit having an oil fuel supply line to be joined to the gas fuel supply line upstream of the injector and for supplying oil fuel to the engine; a gas fuel recovery unit having a gas fuel recovery line connected to the outlet and for recovering surplus gas fuel; and an oil fuel recovery unit having an oil fuel recovery line branching from the gas fuel recovery line downstream of the outlet and for recovering surplus oil fuel. Therefore, the fuel supply system can increase engine performance and minimize rise in price.

Description

fuel supply system

The present invention relates to a fuel supply system.

In general, various engines, such as a diesel engine, a gas turbine engine, and a dual fuel engine, have been developed as large engines mounted on ships. Among them, a dual fuel engine is widely used in ships due to the advantage that two fuels, for example, gas (LNG, etc.) and oil (diesel, etc.) can be used in parallel.

Ships equipped with such a dual fuel engine are classified into high-pressure engines (ME-GI) and low-pressure engines (X-DF, etc.) ME-LGIP, X-DF) or 4-stroke engine (DFDE).

The dual fuel engine operates using one of a gas mode for generating propulsion driving force using a gas such as LNG or LPG as a main fuel, and an oil mode for generating propulsion driving force using oil as a main fuel.

To this end, a dual fuel engine has a cylinder having a combustion chamber, a piston that reciprocates in the vertical direction in the cylinder, an oil fuel injector that injects oil fuel into the cylinder, an exhaust valve for discharging exhaust gas burned from the cylinder, and exhaust exhaust from the cylinder. An exhaust gas receiver that receives gas, a scavenging receiver that supplies air into the cylinder, a gas fuel injector that supplies gas fuel to the inside of the cylinder, a pilot injector that injects a small amount of oil fuel as pilot fuel for ignition in gas mode, etc. includes

When such an engine operates in gas mode, the piston compresses the scavenging air (scavenge air and gas fuel in the case of a low-pressure engine) (in the case of a high-pressure engine, after compression, gas fuel is injected), and uses a pilot injector to ignite the piston by explosive force. implement descent. On the other hand, when operating in oil mode, an explosion may be generated using an oil fuel injector instead of a gas fuel injector.

However, for such a dual fuel engine, there is no space to install two or more injectors of the size for injecting gas fuel and oil fuel respectively for a medium speed engine with a small cylinder size. .

The present invention was created to solve the problems of the prior art as described above, and an object of the present invention is to effectively operate gas mode and oil mode for an engine equipped with an injector capable of injecting both gas fuel and oil fuel. It is to provide a fuel supply system that minimizes price increase while increasing engine performance by configuring the system to be implemented.

A fuel supply system according to an aspect of the present invention is a system for supplying fuel to an engine operating in a gas mode consuming gas fuel or an oil mode consuming oil fuel, wherein the engine is The fuel or oil fuel is supplied, and the surplus gas fuel or the surplus oil fuel is recovered through one outlet, has a gas fuel supply line connected to the injector, and supplies the gas fuel to the engine gas fuel supply unit; an oil fuel supply unit having an oil fuel supply line joined to the gas fuel supply line upstream of the injector and supplying oil fuel to the engine; a gas fuel recovery unit having a gas fuel recovery line connected to the outlet and recovering an excess gas fuel; and an oil fuel recovery unit having an oil fuel recovery line branched from the gas fuel recovery line downstream of the outlet, and recovering excess oil fuel.

Specifically, the gas fuel supply unit, a fuel tank; a high-pressure pump provided in the gas fuel supply line to pressurize the gas fuel in the fuel tank in response to the required pressure of the engine; and a heat exchanger provided in the gas fuel supply line to change the temperature of gas fuel, wherein the oil fuel supply line may be joined to a point downstream of the high-pressure pump in the gas fuel supply line.

Specifically, the gas fuel recovery line is joined to an upstream point of the high-pressure pump in the gas fuel supply line, so that the surplus gas fuel is transferred to the gas fuel supply line upstream of the high-pressure pump and re-introduced into the engine. can do.

Specifically, when the engine is switched between the gas mode and the oil mode, the engine may further include a recovery tank for recovering the gas fuel or oil fuel remaining in the engine.

Specifically, the recovery tank recovers the gas fuel remaining in the engine when the engine is switched from the gas mode to the oil mode and the oil fuel is supplied to the engine in the switching mode, or the engine is in the oil mode. The oil fuel remaining in the engine may be recovered when the engine is switched to the gas mode and the gas fuel is supplied to the engine.

Specifically, it may further include a recovered fuel branch line branched from the gas fuel recovery line downstream of the outlet and connected to the recovery tank.

Specifically, the recovered fuel branch line may be branched downstream of a point where the oil fuel recovery line is branched from the gas fuel recovery line.

Specifically, in the switching mode in which the engine is switched from the gas mode to the oil mode, the upstream part of the junction of the oil fuel supply line in the gas fuel supply line and the branch point of the recovered fuel branch line in the gas fuel recovery line When the downstream part of and the oil fuel recovery line are closed, the oil fuel supply line and the recovered fuel branch line are opened, and the engine is switched from the oil mode to the gas mode in a switching mode, the oil fuel supply line and the In the gas fuel recovery line, a downstream portion of a branch point of the recovered fuel branch line and the oil fuel recovery line may be closed, and the gas fuel supply line and the recovered fuel branch line may be opened.

The fuel supply system according to the present invention uses an engine that injects both gas fuel and oil fuel using a single injector, and in order to smoothly supply fuel to such an engine, fuel supply and surplus in gas mode and oil mode By efficiently controlling fuel recovery, stable operation can be ensured.

1 to 5 are conceptual views of a fuel supply system according to an embodiment of the present invention.

The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In the present specification, in adding reference numbers to the components of each drawing, it should be noted that only the same components are given the same number as possible even though they are indicated on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. For reference, in this specification, gas fuel (liquefied gas) may be heavy hydrocarbons such as LPG (propane, butane, etc.) or ammonia, methanol, ethanol, etc., but is not limited thereto, and the boiling point is lower than room temperature or the flash point is lower than 60°C , can encompass all substances having a calorific value.

The present invention includes a ship equipped with a fuel supply system as described below. At this time, a ship is a concept that includes all gas carriers, merchant ships that transport cargo or people other than gas, FSRUs, FPSOs, bunkering vessels, and offshore plants, but note that it may be a liquefied gas carrier as an example.

Although not shown in the drawings of the present invention, of course, a pressure sensor (PT), a temperature sensor (TT), etc. may be provided at an appropriate position without limitation, and the measurement value by each sensor is dependent on the operation of the components described below. It can be used in various ways without limitation.

1 to 5 are conceptual views of a fuel supply system according to an embodiment of the present invention.

For reference, in FIGS. 2 to 5 , a dotted line indicates a portion where the flow of the fluid is blocked, and a solid line indicates a portion where the flow of the fluid is allowed. In addition, Figure 2 shows the fluid flow when the engine 100 is operated in the gas mode in the present invention, Figure 3 is the engine 100 in the present invention shows the fluid flow in the switching mode for switching from the gas mode to the oil mode indicates. In addition, FIG. 4 shows the fluid flow when the engine 100 operates in the oil mode in the present invention, and FIG. 5 shows the fluid flow when the engine 100 is switched from the oil mode to the gas mode in the present invention. indicates.

1 to 5 , the fuel supply system 1 according to an embodiment of the present invention is a system for supplying fuel to the engine 100 , wherein the engine 100 is a dual fuel engine 100 . can That is, the engine 100 is an engine 100 capable of consuming gas fuel and oil fuel, respectively, and when the engine 100 is operated by consuming gas fuel, the engine 100 is operated by consuming oil fuel in gas mode. It can be referred to as oil mode.

In particular, the engine 100 of the present invention operates in gas mode or oil mode, but does not include the gas fuel injector 110 and the oil fuel injector 110 , respectively, but gas fuel through one fuel injector 110 . Or the supply of oil fuel is made.

That is, as shown in the drawing, the engine 100 to which the present invention is applied includes a fuel injector 110 for supplying gas fuel and oil fuel integrated into one. In this case, the fuel injector 110 is disposed above the combustion chamber, and may inject gas fuel or oil fuel into the combustion chamber at an appropriate time between the bottom dead center and top dead center of the piston.

The engine 100 of the present invention is an engine 100 operated by receiving gas fuel in a liquid phase, and may be an LPG engine, ME-LGI, or the like. At this time, the engine 100 may have a structure in which it is difficult to fine-tune the amount of fuel in comparison with the case where gas fuel is supplied in the gaseous phase, so that the engine 100 receives a sufficient amount of liquid fuel and discharges the surplus liquid fuel.

That is, among the gas fuel or oil fuel introduced into the engine 100 , the surplus gas fuel or oil fuel mixed with the lubricating oil used in the engine 100 while passing through the interior of the engine 100 is discharged to the outside of the engine 100 . can be emitted. At this time, the engine 100 may have a structure in which the surplus gas fuel or the surplus oil fuel is recovered through one outlet, similar to the integrated supply of gas fuel and oil fuel through one fuel injector 110 . have.

In this case, the exhaust port may be disposed at an appropriate position above the combustion chamber, or may be provided integrally with the fuel injector 110 . Therefore, gas fuel or oil fuel is guided into the combustion chamber through the fuel injector 110 according to the operation mode of the engine 100, and the surplus gas fuel, etc. is discharged to the outside of the combustion chamber through an outlet provided in the fuel injector 110. can

In addition, the engine 100 is provided with an intake port 130, and the intake port 130 is provided on the upper side of the combustion chamber as shown in the drawing, so that air introduced from a scavenging air receiver (not shown) can be guided into the combustion chamber.

The engine 100 of the present invention may be a high-pressure engine or a low-pressure engine, and in the case of a high-pressure engine, the intake port 130 may be connected to the upper side of the combustion chamber as shown in the drawing, but in the case of a low-pressure engine, the intake port 130 is Unlike the drawing, it may be disposed just above the bottom dead center in the combustion chamber. That is, the position of the intake port 130 is not limited to that shown in the drawings. In addition, although not shown in the drawings, it goes without saying that an exhaust port (not shown) may be provided at an appropriate location in the engine 100 .

In addition, the engine 100 is provided with a pilot injector 120 . When the engine 100 operates in the gas mode consuming gas fuel or in the oil mode consuming oil fuel, the pilot injector 120 may inject pilot fuel into the combustion chamber to ignite.

A pilot fuel supply line L60 is provided in the pilot injector 120, and the pilot fuel supply line L60 may guide oil fuel or the like as pilot fuel into the combustion chamber through a pilot fuel supply unit (not shown). . For reference, in the present invention, the pilot fuel may be the same as the oil fuel, and the pilot fuel supply unit may be provided as a part of the oil fuel supply unit 20 to be described later.

A pilot fuel recovery line L61 is provided in the pilot injector 120 . As described in the fuel injector 110 , the pilot injector 120 may also be provided to have a structure capable of recovering an excess liquid pilot fuel, and the pilot fuel recovery line L61 is a pilot injector 120 surplus pilot fuel. It is connected to the part where the fuel is discharged.

The pilot fuel recovery line L61 may recover the surplus pilot fuel upstream of the pilot fuel supply unit, or store it in a separate storage unit and reuse it later. It is also possible to recover the pilot fuel upstream of the supply unit 20 or to the recovery tank 50 .

Hereinafter, components constituting the fuel supply system 1 of the present invention for supplying fuel to the engine 100 as described above will be described.

The fuel supply system 1 according to an embodiment of the present invention includes a gas fuel supply unit 10 , an oil fuel supply unit 20 , a gas fuel recovery unit 30 , an oil fuel recovery unit 40 , and a recovery tank 50 . ) is included.

The gas fuel supply unit 10 supplies gas fuel to the engine 100 . The gas fuel supply unit 10 includes a cargo tank 11 , a fuel tank 12 , a high-pressure pump 13 , and a heat exchanger 14 , and includes a gas fuel supply line L10 for delivery of gas fuel. .

The cargo tank 11 is a plurality of cargo tanks provided in the ship which is a liquefied gas carrier. Of course, if the ship is a ship other than the liquefied gas carrier, the cargo tank 11 may be a tank or container that is separately added to the inside or the outside of the ship.

The cargo tank 11 is a tank for storing gas fuel in a low-temperature liquid state at atmospheric pressure, and various insulating structures may be added to the wall to prevent vaporization of the gas fuel. In addition, the cargo tank 11 may be a membranous tank or an independent tank, and the shape or specification thereof is not limited.

Gas fuel may be delivered from the cargo tank 11 to the fuel tank 12 to be described later, and the gas fuel is a gas fuel supply line L10 connected from the cargo tank 11 to the fuel tank 12 (cargo tank ( 11) and the gas fuel supply line L10 between the fuel tank 12 is transferred from the cargo tank 11 to the fuel tank 12 through a gas fuel delivery line (which may be referred to as a gas fuel delivery line). The gas fuel delivered to the fuel tank 12 is used as the fuel of the engine 100 .

For reference, in this specification, the engine 100 may be a propulsion engine for propelling a ship or a power generation engine for covering an in-board power load, and as described above, the fuel injector 110, the pilot injector 120, the intake port ( 130) and the like.

A transfer pump (not shown) may be assigned to the cargo tank 11 , and a gas fuel supply line L10 may be connected to the transfer pump. The transfer pump may be provided inside the cargo tank 11, and may be provided as a submerged type submerged in gas fuel.

The transfer pump may be provided in some of the plurality of cargo tanks 11 . The cargo tank 11 is basically for the purpose of transporting cargo, and a cargo pump (unloading pump, stripping pump, etc., not shown) for unloading cargo is at least two for each cargo tank 11 . It is provided, at least one cargo tank 11 is to use the gas fuel stored therein as fuel, such as the engine 100 (ME-LGI), in addition to the cargo pump, a transfer pump may be added.

For example, when four cargo tanks 11 are provided side by side in the longitudinal direction of the ship, gas fuel stored in the fourth cargo tank 11 adjacent to the engine room in which the engine 100 is accommodated is delivered to the fuel tank 12 . After being used as fuel of the engine 100, a transfer pump may be provided only in the fourth cargo tank 11 for this purpose.

The fuel tank 12 stores gas fuel as fuel to be supplied to the engine 100 . The fuel tank 12 may be of the same or different type as the stand-alone (SPB type, MOSS type) or membrane-type cargo tank 11 for storing a large amount of gas fuel at atmospheric pressure, and storing gas fuel at high pressure (Type) C, pressure vessel type).

At this time, the fuel tank 12 may store the gas fuel above the critical pressure (eg, around 18 bar), or store it below the critical pressure (eg, around 8 bar), inside or outside the wall to prevent vaporization of the gas fuel. A heat insulating structure may be provided on at least one side of the.

The fuel tank 12 may be mounted on the upper deck in a ship, and is provided to be supported on the upper deck through a saddle. The fuel tank 12 does not interfere with the components (manifold, etc.) for gas fuel loading/unloading of the cargo tank 11 on the upper deck, and is to be disposed at a position that does not block the visibility when the vessel is sailing. can For example, the fuel tank 12 may be provided on the port side or starboard side of the bow on the upper deck. In this case, the fuel tank 12 may be referred to as a deck tank.

The fuel tank 12 may be configured to temporarily store gas fuel between the cargo tank 11 and the engine 100 . Accordingly, the gas fuel supply line L10 may be connected from the cargo tank 11 to the fuel tank 12 , and from the fuel tank 12 to the engine 100 , respectively. Alternatively, the engine 100 may directly use the gas fuel of the cargo tank 11 , and for this purpose, the gas fuel supply line L10 is configured to bypass the fuel tank 12 between the cargo tank 11 and the engine 100 . may be provided.

Gas fuel may be delivered from the cargo tank 11 to the fuel tank 12 by a transfer pump immersed in the cargo tank 11, and the gas fuel stored in the fuel tank 12 is It can be managed at an appropriate level/pressure. Conversely, it is also possible that the gas fuel is returned from the fuel tank 12 to the cargo tank 11 .

The gas fuel stored in the fuel tank 12 may be delivered from the fuel tank 12 to the engine 100 through a high-pressure pump 13, which will be described later. Accordingly, a high-pressure pump 13 , a heat exchanger 14 , and the like may be provided in the gas fuel supply line L10 extending from the fuel tank 12 to the engine 100 .

The high-pressure pump 13 is provided on the gas fuel supply line L10 extending from the fuel tank 12 to the engine 100 , and responds to the gas fuel in the fuel tank 12 to the required pressure of the engine 100 . to pressurize The type of the high-pressure pump 13 is not particularly limited, and a plurality of the high-pressure pumps 13 may be provided in parallel to be able to back up each other as shown in the drawing.

The high-pressure pump 13 may be provided upstream of the heat exchanger 14 to be described later as shown in the drawing, or may be provided downstream of the heat exchanger 14 unlike the drawing. In the latter case, the high-pressure pump 13 may pressurize the gas fuel whose temperature is controlled by the heat exchanger 14 to the pressure required by the engine 100 .

In order to suppress the occurrence of cavitation in the gas fuel pressurization process of the high-pressure pump 13 , the gas fuel may be introduced into the high-pressure pump 13 in a liquid phase. When the heat exchanger 14 is provided upstream of the high-pressure pump 13, the heat exchanger 14 may control the temperature of the gas fuel in consideration of the above.

The pressure of the gas fuel sucked into the high-pressure pump 13 may correspond to the pressure of the gas fuel discharged from the fuel tank 12 or the cargo tank 11 . In addition, as will be described later, it may also correspond to the pressure of gas fuel recovered from the engine 100 .

The heat exchanger 14 is provided downstream of the high-pressure pump 13 to change the temperature of the gas fuel. The heat exchanger 14 may increase or decrease the temperature of the gas fuel, and thus may be referred to as a fuel conditioner.

For example, during the initial operation of this embodiment, since the flow rate of the high-temperature gas fuel recovered from the engine 100 is large, the heat exchanger 14 can lower the temperature of the gas fuel, and when entering into stable operation, the heat exchanger ( 14) can increase the temperature of gas fuel.

The heat exchanger 14 may be provided downstream of the high-pressure pump 13 as shown in the drawing, or unlike the drawing, the heat exchanger 14 may be provided upstream of the high-pressure pump 13 . In the latter case, the heat exchanger 14 may control the temperature of the gas fuel below the boiling point of the gas fuel so that the gaseous gas fuel does not flow into the high-pressure pump 13 .

The heat exchanger 14 may implement heat exchange with gas fuel by using various heat exchange media. For example, the heat exchange medium may be seawater, fresh water, glycol water, exhaust gas, etc., but is not limited thereto.

The gas fuel supply unit 10 may further include a low pressure pump (not shown). The low pressure pump properly pressurizes the gas fuel in the fuel tank 12 and delivers it to the engine 100 . The low pressure pump may be provided inside or outside the fuel tank 12 , and may be provided on the gas fuel supply line L10 connected from the fuel tank 12 to the engine 100 .

The low-pressure pump may pressurize the gas fuel to a pressure lower than the required pressure of the engine 100 . Specifically, the low-pressure pump may pressurize the gas fuel according to the suction pressure (eg, 20 bar) of the high-pressure pump 13 disposed downstream. That is, the low-pressure pump may increase the pressure of the gas fuel by the differential pressure between the internal pressure of the fuel tank 12 and the suction pressure of the high-pressure pump 13 . However, when the storage pressure of the fuel tank 12 corresponds to the suction pressure of the high-pressure pump 13, the low-pressure pump may be omitted.

In addition, the gas fuel supply unit 10 may include a filter (not shown) downstream of the high-pressure pump 13 . The filter is configured to filter out impurities, and may be disposed upstream of the high-pressure pump 13 as well as downstream of the high-pressure pump 13 .

The gas fuel supply line L10 of the gas fuel supply unit 10 is connected to the fuel injector 110 . At this time, the fuel injector 110 is configured to inject both gas fuel and oil fuel into the combustion chamber as described above.

A gas fuel supply valve 15 may be provided downstream of the high-pressure pump 13 in the gas fuel supply line L10 . The gas fuel supply valve 15 is opened and closed when the operation of the engine 100 is switched to a gas mode, an oil mode, a switching mode, and the like, so that it is possible to control whether gas fuel is supplied.

The gas fuel supply valve 15 is configured as a single train together with the gas fuel recovery valve 32 of the gas fuel recovery unit 30 to be described later, and may be referred to as a fuel valve train (FVT).

A management unit (not shown) for discharging the flowing or remaining gas fuel to the outside may be provided in the fuel tank 12 and/or the gas fuel supply line L10 . The management unit may receive gas fuel from the gas fuel supply line L10, etc. to vent the gas fuel existing in the gas fuel supply line L10, etc. to the outside in an emergency situation, or the fuel tank 12 or gas fuel supply A purging gas may be supplied into the gas fuel supply line L10 in order to remove the gas fuel remaining in the line L10.

To this end, the management unit includes a purging gas supply unit (not shown) that injects the purging gas into the fuel tank 12 or the gas fuel supply line L10, and the fuel tank 12 or the gas fuel supply line L10. It may include a temporary storage container (not shown) for temporarily storing gas fuel, and the like, and the temporary storage container is connected to a vent mast (not shown) to release the gas fuel into the atmosphere, or to the fuel tank 12 . It can be connected to recycle gas fuel.

The oil fuel supply unit 20 supplies oil fuel to the engine 100 . The oil fuel supply unit 20 includes an oil tank 21 and an oil pump 22 , and delivers oil fuel through an oil fuel supply line L20 .

The oil tank 21 stores oil fuel. The oil tank 21 is a configuration for storing liquid oil fuel at room temperature, and may not have an insulating structure unlike the cargo tank 11 or the fuel tank 12 described above.

The oil tank 21 may be provided in a hull-shaped structure in the hull, and a part of the interior space of the hull may be diverted to the oil tank 21 . For example, a part of the topside tank of the ballast tank, the void space of the bow, the empty space in front of the engine room, etc. may be utilized as the oil tank 21 .

The oil pump 22 transfers the oil fuel stored in the oil tank 21 to the engine 100 . The oil pump 22 is provided on the oil fuel supply line L20 connected from the oil tank 21 to the engine 100 , and can pressurize the liquid oil fuel to the required pressure of the engine 100 .

Similar to the high-pressure pump 13 described above, a plurality of oil pumps 22 may be provided in parallel to enable mutual backup. Also, the discharge pressures of the oil pump 22 and the high-pressure pump 13 may be the same since they both correspond to the required pressure of the engine 100, or the oil pump 22 for smooth conversion from the gas mode to the oil mode. The discharge pressure may be slightly higher than the discharge pressure of the high-pressure pump 13 .

The oil fuel supply line L20 of the oil fuel supply unit 20 is indirectly connected to the fuel injector 110 through the gas fuel supply line L10 . The oil fuel supply line L20 may be provided to join the gas fuel supply line L10 at a point upstream of the fuel injector 110 and downstream of the high-pressure pump 13 .

That is, the gas fuel is delivered to the fuel injector 110 through the gas fuel supply line L10, and the oil fuel is an oil fuel supply line L20 and a downstream part of the gas fuel supply line L10 (oil fuel supply line L20). ) may be transmitted to the fuel injector 110 through the downstream portion of the junction.

An oil fuel supply valve 23 may be provided downstream of the oil pump 22 in the oil fuel supply line L20 . Like the gas fuel supply valve 15 , the oil fuel supply valve 23 is opened and closed when the operation of the engine 100 is switched to a gas mode, an oil mode, a switching mode, etc. to control whether oil fuel is supplied or not. can do.

However, since the engine 100 operating in a stable state will operate in any one of the gas mode and the oil mode, the oil fuel supply valve 23 may have an open/close state opposite to that of the gas fuel supply valve 15 .

The gas fuel recovery unit 30 recovers the surplus gas fuel. Unlike commercial engines 100 (ME-GI, XDF, etc.) that receive and consume LNG in the gas phase, the engine 100 (ME-LGI, etc.) in the present invention receives and consumes LPG in liquid phase and consumes the surplus. It has a structure for discharging liquid fuel.

This is because, as described above, fine control of the fuel supply amount is not easy in the liquid phase, unlike the gas phase, so that the engine 100 receives a sufficient amount of the liquid fuel, thereby generating an excess of fuel.

However, the gas fuel recovered from the engine 100 is gas fuel that has passed through the interior of the engine 100 and has a temperature/pressure corresponding to the required pressure of the engine 100 (for example, around 45 bar, 50 degrees C or more). ), lubricating oil used in the engine 100 may be mixed inside the gas fuel.

That is, since lubricating oil is mixed in the excess gas fuel recovered from the engine 100 , it is preferable not to deliver the recovered gas fuel to the cargo tank 11 in order to prevent cargo contamination.

Therefore, the gas fuel recovery unit 30 is connected to the exhaust port of the engine 100 and through the gas fuel recovery line L30 that joins the upstream point of the high-pressure pump 13 in the gas fuel supply line L10, the engine ( The surplus gas fuel returned from 100) may be transferred to the high-pressure pump 13 instead of the cargo tank 11 to be re-introduced into the engine 100 .

That is, the gas fuel recovery line (L30) passes through the interior of the engine 100, and the surplus liquid gas fuel mixed with the lubricating oil used in the engine 100 is transferred to the gas fuel supply line (L10) upstream of the high-pressure pump 13. ) to be re-introduced into the engine 100, it is possible to prevent contamination of the gas fuel in the cargo tank 11 due to the lubricating oil.

A pressure reducing valve and a cooler 31 may be provided in the gas fuel recovery line L30. The pressure reducing valve depressurizes the surplus liquid gas fuel discharged from the engine 100 and mixed with lubricating oil. The pressure reducing valve may be a Joule-Thompson valve.

The cooler 31 cools the gas fuel decompressed by the pressure reducing valve in the gas fuel recovery line L30 so that it flows into the high pressure pump 13 in a liquid phase. The cooler 31 may utilize various refrigerants that are not limited, and may cool the gas fuel below the boiling point of the depressurized gas fuel. For example, the cooler 31 may use seawater as a refrigerant, and in this case, the heat exchanger 14 and the cooler 31 may be integrally connected by one refrigerant supply unit.

Since the cooling by the cooler 31 can be made in consideration of mixing with the gas fuel delivered from the fuel tank 12 to the high-pressure pump 13, the cooler 31 has a temperature somewhat higher than the boiling point of the depressurized gas fuel. It is also possible to control the cooling of gas fuel with the furnace.

The liquid (or close to liquid) gas fuel cooled by the cooler 31 is mixed upstream of the high-pressure pump 13 in the gas fuel supply line L10 through the gas fuel recovery line L30, and the gas fuel A mixer (not shown) may be provided at a point where the recovery line L30 is connected to the gas fuel supply line L10 .

Upstream of the cooler 31 in the gas fuel recovery line L30, a gas fuel recovery valve 32 may be provided. The gas fuel recovery valve 32 is a gas fuel supply line in which the surplus gas fuel discharged from the outlet of the engine 100 when the engine 100 operates in a gas mode or a switching mode (switching from a gas mode to an oil mode) It is opened to be returned to (L10).

On the other hand, the gas fuel recovery valve 32 may be closed when the engine 100 operates in an oil mode or the like. This is because, in this case, the excess oil fuel will be discharged from the outlet of the engine 100 . That is, opening and closing of the gas fuel recovery valve 32 may be controlled according to the operation mode of the engine 100 .

The gas fuel recovery unit 30 may further include a collection tank (not shown) and/or a knockout drum (not shown). The collection tank may separate the recovered gas fuel from gas-liquid to prevent gaseous gas fuel from being delivered to the high-pressure pump 13 . That is, the collection tank collects gas fuel from the gas fuel recovery line L30 and delivers only liquid gas fuel to the high-pressure pump 13 , thereby ensuring stable operation of the high-pressure pump 13 .

The knockout drum may receive the gas fuel recovered from the engine 100 from the collection tank, and filter impurities (lubricating oil, etc.) included in the gas fuel. The knockout drum separates the lubricating oil from the gas fuel introduced therein. For example, the knockout drum may discharge gas fuel in a gaseous phase and lubricating oil in a liquid phase, and the knockout drum may implement a gas-liquid separation function similarly to a collection tank.

However, the knockout drum may use a heating unit such as tracing to promote vaporization of gas fuel, and the tracing may be configured to use a medium such as steam or seawater as a heat source or to heat using electricity. .

The knockout drum may heat gas fuel mixed with lubricating oil with a heating unit, discharge the gas fuel through a vent mast (not shown), etc., and drain the lubricating oil from the bottom for treatment (recycle).

The oil fuel recovery unit 40 recovers excess oil fuel. As described in the gas fuel recovery unit 30 , the engine 100 may discharge excess oil fuel to the outlet during operation. At this time, the oil fuel recovery unit 40 may recover the oil fuel discharged through the outlet, and the recovered oil fuel may be delivered to the oil tank 21 .

Since the oil fuel stored in the oil tank 21 of this embodiment is fuel for the operation of the engine 100 rather than cargo for transportation, there is a problem even if the lubricating oil of the engine 100 is mixed with the oil fuel in the oil tank 21 . doesn't happen Accordingly, the oil fuel recovery unit 40 may directly recover the excess oil fuel discharged from the engine 100 to the oil tank 21 .

Of course, instead of being directly recovered to the oil tank 21 , the oil fuel may be recovered upstream of the oil pump 22 from the oil fuel supply line L20 . For reference, even in the case of gas fuel, the gas fuel may be directly recovered to the fuel tank 12 instead of being recovered to the upstream of the high-pressure pump 13 .

The oil fuel recovery unit 40 may include an oil fuel recovery line L40 for recovering oil fuel, and the oil fuel recovery line L40 is branched from the gas fuel recovery line L30 downstream of the outlet.

The engine 100 is provided in a structure to recover all of the surplus gas fuel or the surplus oil fuel through one outlet, and the surplus gas fuel is a high-pressure pump through a gas fuel recovery line (L30) directly connected to the outlet. (13) It is recovered upstream, and the surplus oil fuel passes through the upstream part of the gas fuel recovery line L30 (the upstream part of the point where the oil fuel recovery line L40 branches off) through the oil fuel recovery line L40. It may be recovered to the oil tank 21 or the like.

The recovery tank 50 stores the surplus gas fuel or surplus oil fuel discharged from the engine 100 . The recovery tank 50 may have a different configuration from the temporary storage container of the management unit described above, and the temporary storage container is a configuration connected to the supply side of the gas fuel, such as the fuel tank 12 or the gas fuel supply line (L10). On the other hand, the recovery tank 50 is configured to be connected to the recovery side of the gas fuel, such as the gas fuel recovery line (L30) in which the surplus gas fuel is recovered from the engine 100 .

When the engine 100 operates in the gas mode, the excess gas fuel is recovered upstream of the high-pressure pump 13 , and when the engine 100 operates in the oil mode, the excess oil fuel is recovered to the oil tank 21 , etc. can be However, when the engine 100 is switched from the gas mode to the oil mode or the oil mode is switched from the oil mode to the gas mode, the fuel remaining in the engine 100 may be different from the fuel supplied to the engine 100 . have.

In this case, the excess fuel discharged from the engine 100 may be recovered to the recovery tank 50 . That is, the recovery tank 50 recovers the gas fuel or oil fuel remaining in the engine 100 when the engine 100 is switched between the gas mode and the oil mode.

Specifically, the recovery tank 50 recovers the gas fuel remaining in the engine 100 when the engine 100 is switched from the gas mode to the oil mode and the oil fuel is supplied to the engine 100 in the switching mode. Conversely, when the engine 100 is switched from the oil mode to the gas mode and gas fuel is supplied to the engine 100 in the switching mode, the oil fuel remaining in the engine 100 may be recovered.

To this end, a recovered fuel branch line L50 may be provided in the recovery tank 50 . The recovered fuel branch line (L50) is branched from the gas fuel recovery line (L30) downstream of the outlet, and delivers gas fuel or oil fuel to the recovery tank (50).

The recovered fuel branch line L50 may be branched from the gas fuel recovery line L30 to the downstream of the branching point of the oil fuel recovery line L40, but is not limited thereto, and oil fuel recovery on the gas fuel recovery line L30 The recovered fuel branch line L50 may be branched upstream of the branch point of the line L40.

A recovered fuel branch valve 51 may be provided in the recovered fuel branch line L50. The recovery fuel branch valve 51 may be opened when it is necessary to recover the surplus gas fuel or the surplus oil fuel to the recovery tank 50, or the surplus gas fuel or the surplus oil fuel recovers the gas fuel. When the fuel is recovered through the unit 30 or the oil fuel recovery unit 40 , the recovered fuel branch valve 51 may be closed.

The gas fuel supply valve 15, the gas fuel recovery valve 32, the oil fuel supply valve 23, the oil fuel recovery valve 41, etc. mentioned in the present invention are a vent line ( Symbols not shown) may be provided to enable delivery of fuel. Each of these valves may be provided in plurality or may be configured as a three-way valve, but is not limited thereto. The opening and closing operations of the valves for controlling the flow of gas fuel and oil fuel will be described in detail below with reference to FIG. 2 and the like.

According to ship safety rules, the engine 100, which is configured in a similar manner to ME-LGIP, etc. and consumes gas fuel, consumes all remaining gas fuel in the line connected to the engine 100 when the fuel is switched from the gas mode to the oil mode. Purging with nitrogen (inert gas) is essential.

Gas fuel mixed with nitrogen during purging passes through a knockout drum that may be provided in the gas fuel recovery unit 30 and is discharged into the atmosphere in a gaseous state through a vent mast.

However, unlike LNG and ammonia, which have a lower density than air and can be easily discharged into the air, gas fuel with a higher density than air, such as LPG, is more likely to collect to the bottom even if discharged into the atmosphere. At this time, there is a risk of an explosion at any time if the gas fuel accumulates above the explosion limit.

In order to solve this problem, the present invention uses the oil fuel pressurized in the fuel conversion step (conversion of fuel from gas mode to oil mode) of the engine 100 to discharge the remaining gas fuel to the recovery tank 50 for a certain period of time. , it is possible to solve possible safety problems when venting residual gas fuel. At this time, when the residual gas fuel in the line connected to the engine 100 is completely removed, the fuel conversion process may be completed while the oil fuel is recovered using the oil fuel recovery unit 40 .

When the oil fuel and gas fuel are stored in a mixed state in the recovery tank 50, the mixed fuel can be processed on land, so that the risk of discharging gas fuel with high density into the air during operation can be minimized. Moreover, since the emission of vaporized fuel during operation is minimized, environmental protection effects can also be achieved.

Of course, the gas fuel vaporized among the mixed fuel is discharged from the recovery tank 50 to the vent mast, and it is also possible to solve the risk of an increase in internal pressure of the recovery tank 50 due to the vaporized gas fuel.

Hereinafter, the flow of fuel according to the operation mode of the engine 100 in the present invention will be described in detail with reference to FIGS. 2 to 5 .

2 shows a state in which the engine 100 is stably operated in a gas mode consuming gas fuel. According to FIG. 2 , the gas fuel supply valve 15 provided in the gas fuel supply line L10 is opened, and the oil fuel supply valve 23 provided in the oil fuel supply line L20 is closed.

In addition, the gas fuel recovery valve 32 provided in the gas fuel recovery line L30 is opened, the oil fuel recovery valve 41 provided in the oil fuel recovery line L40 is closed, and the recovered fuel branch line L50 is closed. The recovered fuel branch valve 51 provided in the is also closed.

Therefore, in this case, the gas fuel is supplied into the engine 100 through the fuel injector 110 along the gas fuel supply line L10, and the surplus gas fuel is discharged through the outlet of the fuel injector 110 to be gas fuel. It may be recovered upstream of the high-pressure pump 13 along the recovery line L30 and the like.

On the other hand, the oil fuel is not supplied to the engine 100 as both the supply and recovery flows are blocked, and also the recovered fuel branch valve 51 is blocked, so that the surplus fuel is not transferred to the recovery tank 50 .

In order for the engine 100 to switch from the gas mode to the oil mode, it goes through the state shown in FIG. 3 . 3 shows the fuel flow when the engine 100 is in a switching mode for switching from the gas mode to the oil mode.

According to FIG. 3 , the gas fuel supply valve 15 is blocked to stop the supply of the gas fuel, while the oil fuel supply valve 23 is opened to start the supply of the oil fuel. At this time, gas fuel may remain in the engine 100 and the lines connected to the engine 100 .

Accordingly, in a state in which the gas fuel recovery valve 32 and the oil fuel recovery valve 41 are blocked and the recovery fuel branch valve 51 is opened, the oil fuel flowing into the engine 100 remains in and around the engine 100 . While pushing one gas fuel, gas fuel and oil fuel may be mixed and delivered to the recovery tank 50 along the recovered fuel branch line L50.

After that, when all of the gas fuel remaining in the engine 100 is processed, the recovery fuel branch valve 51 is blocked and the oil fuel recovery valve 41 is opened as shown in FIG. 4 . Accordingly, while the oil fuel is supplied to the engine 100 through the oil fuel supply line L20, and the surplus oil fuel is recovered to the oil tank 21 through the oil fuel recovery line L40, the engine 100 is It can be operated stably in oil mode.

On the other hand, when the engine 100 is in the switching mode to switch from the oil mode to the gas mode, the oil fuel supply valve 23 is blocked to stop the supply of oil fuel as shown in FIG. The gas fuel supply valve 15 is opened to

Also, in this case, as in FIG. 3 , in the state in which the oil fuel recovery valve 41 and the gas fuel recovery valve 32 are closed, the recovered fuel branch valve 51 is opened. Accordingly, while gas fuel is injected into the engine 100 , the oil fuel remaining in the engine 100 may be delivered to the recovery tank 50 together with the gas fuel.

When all of the oil fuel remaining in the engine 100 is removed, the recovered fuel branch valve 51 is blocked and the gas fuel recovery valve 32 is opened in the state of FIG. 2 , and the engine 100 stably operates the gas fuel to enter gas mode.

As described above, in this embodiment, for the engine 100 having a structure capable of supplying both gas fuel and oil fuel with one fuel injector 110 , supply and recovery of fuel when the gas mode and the oil mode are switched effectively By processing, it is possible to ensure stable and efficient operation of the engine 100 .

Although the present invention has been described in detail through specific examples, it is intended to describe the present invention in detail, and the present invention is not limited thereto. It will be clear that the transformation or improvement is possible.

All simple modifications or changes of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

1: fuel supply system 10: gas fuel supply unit
11: cargo tank 12: fuel tank
13: high pressure pump 14: heat exchanger
15: gas fuel supply valve 20: oil fuel supply part
21: oil tank 22: oil pump
23: oil fuel supply valve 30: gas fuel recovery unit
31: cooler 32: gas fuel recovery valve
40: oil fuel recovery unit 41: oil fuel recovery valve
50: recovery tank 51: recovery fuel branch valve
100: engine 110: fuel injector
120: pilot injector 130: intake port
L10: gas fuel supply line L20: oil fuel supply line
L30: gas fuel recovery line L40: oil fuel recovery line
L50: Recovery fuel branch line L60: Pilot fuel supply line
L61: Pilot fuel recovery line

Claims (8)

A system for supplying fuel to an engine operating in a gas mode consuming gas fuel or an oil mode consuming oil fuel,
The engine is
Gas fuel or oil fuel is supplied through one injector, and excess gas fuel or excess oil fuel is recovered through one outlet,
a gas fuel supply unit having a gas fuel supply line connected to the injector and supplying gas fuel to the engine;
an oil fuel supply unit having an oil fuel supply line joined to the gas fuel supply line upstream of the injector and supplying oil fuel to the engine;
a gas fuel recovery unit having a gas fuel recovery line connected to the outlet and recovering an excess gas fuel; and
and an oil fuel recovery unit having an oil fuel recovery line branching from the gas fuel recovery line downstream of the outlet, and recovering an excess oil fuel. The method of claim 1,
The gas fuel supply unit,
fuel tank;
a high-pressure pump provided in the gas fuel supply line to pressurize the gas fuel in the fuel tank in response to the required pressure of the engine; and
It is provided in the gas fuel supply line and includes a heat exchanger for changing the temperature of the gas fuel,
The oil fuel supply line is
a fuel supply system that joins a point downstream of the high-pressure pump in the gas fuel supply line. According to claim 2, The gas fuel recovery line,
A fuel supply system that joins an upstream point of the high-pressure pump in the gas fuel supply line to deliver an excess gas fuel to the gas fuel supply line upstream of the high-pressure pump to re-introduce it to the engine. The method of claim 1,
and a recovery tank configured to recover the gas fuel or oil fuel remaining in the engine when the engine is switched between the gas mode and the oil mode. The method of claim 4, wherein the recovery tank,
When the engine is switched from the gas mode to the oil mode and the oil fuel is supplied to the engine in the conversion mode, the gas fuel remaining in the engine is recovered, or the engine is switched from the oil mode to the gas mode so that the gas fuel is In a switching mode supplied to the engine, the fuel supply system recovers the oil fuel remaining in the engine. 6. The method of claim 5,
The fuel supply system further comprising a recovery fuel branch line branched from the gas fuel recovery line downstream of the outlet and connected to the recovery tank. 7. The method of claim 6, wherein the recovered fuel branch line comprises:
The fuel supply system is branched from the gas fuel recovery line downstream of the branching point of the oil fuel recovery line. 7. The method of claim 6,
When the engine is switched from gas mode to oil mode,
In the gas fuel supply line, an upstream portion of a junction of the oil fuel supply line and a downstream portion of a branch point of the recovered fuel branch line in the gas fuel recovery line and the oil fuel recovery line are closed, and the oil fuel supply line and the recovered fuel branch line is opened,
When the engine is switched from oil mode to gas mode,
In the oil fuel supply line and the gas fuel recovery line, a downstream part of a branch point of the recovered fuel branch line and the oil fuel recovery line are closed, and the gas fuel supply line and the recovered fuel branch line are opened. system.

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