JP2023055419A - Multi-fuel available fuel supply device - Google Patents

Abstract

To provide not only a fuel supply device capable of using fuel such as liquefied ammonia, liquefied petroleum gas, and methanol, but also a fuel supply device in which no return fuel is sent to a fuel tank, and further provide a fuel supply device capable of suitably separating sealing oil and liquefied ammonia fuel or the like even when the sealing oil is contained in return fuel.SOLUTION: In fuel supply device, an engine 1 comprises: a fuel supply line from a fuel tank 2 for storing any one of fuel selected from liquefied ammonia, liquefied petroleum gas and methanol to the engine 1 via a recovery tank 4; and a fuel return line that returns part of the fuel from the engine 1 to the recovery tank 4, where an oil removal recovery device is installed up to the recovery tank 4 of the fuel return line or in the recovery tank 4.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a fuel supply system capable of using various fuels, and more specifically, it is possible to provide a fuel supply system that can use fuels such as liquefied ammonia, liquefied petroleum gas, and methanol. It relates to a fuel supply system in which return fuel is not sent to the fuel tank when used as a fuel tank.

Conventionally, from the viewpoint of environmental regulations based on the prevention of global warming, liquefied ammonia (hereinafter referred to as "LNH ₃ " as required) that does not emit carbon dioxide when burned, liquefied petroleum gas (hereinafter referred to as " Fuels such as LPG) and methanol are required, and fuels are diversifying.
Some of the fuel is returned to the fuel tank for flow control and temperature control, but there is a risk that the return line will be contaminated with seal oil entering from the valve that injects the fuel.

For this reason, depending on the combination with the fuel, there is a risk that the filter or strainer for removing impurities such as particles will be clogged without being mixed with the seal oil. Specifically, in the case of LPG, LPG and seal oil may be mixed, but in the case of LNH ₃ or the like, LNH ₃ and seal oil are not mixed, so there is a problem of clogging as described above.

In addition, when the fuel supply system is stopped, it is necessary to dispose of the fluid inside the system to the outside. Since ammonia, which is toxic, may adversely affect the human body, etc., the ammonia should be removed to protect the human body. Therefore, it is necessary to take measures to remove harm.

Kjeld Aabo, Aammonia-fuelled MAN B&W 2-stroke Dual-fuel Engines, Journal of the Japan Society of Marine Engineering, 2020, No. 56

Methods such as scrubbing and combustion are generally known as methods for removing harm.
When using a scrubber, it is conceivable to store some of the treated water, but there is a problem that the capacity of the tank increases according to the amount used.

Therefore, a method of discharging overboard is required. At that time, domestic standards for rivers are applied as emission standard items, and ammonia nitrogen and oil content are subject to the standards.

Therefore, ammonium nitrogen and oil abatement equipment is required, but if an abatement equipment is installed on board, there is a problem that the amount of waste that must be treated increases depending on the installation situation.
Therefore, in order to remove the liquefied ammonia gas remaining in the piping after the engine is running, a method of pushing out using nitrogen (nitrogen purge) is adopted.

However, in the above nitrogen purge extrusion method, if the discharge destination is the upper part, a supply pressure and flow rate are required for extrusion, and there is a problem that the abatement equipment becomes large due to the relationship between the flow rate and the tower height. there were.

Accordingly, an object of the present invention is not only to provide a fuel supply system that can use fuel such as liquefied ammonia, liquefied petroleum gas, and methanol, but also to provide a fuel supply system that does not send the returned fuel to the fuel tank. is to provide
Another object of the present invention is to provide a fuel supply system capable of suitably separating the seal oil from the liquefied ammonia fuel or the like even if the return fuel contains the seal oil.

Furthermore, other objects of the present invention will become clear from the following description.

The above problems are solved by the following inventions.

(Claim 1)
a fuel supply line from a fuel tank storing any one of fuel selected from liquefied ammonia, liquefied petroleum gas, and methanol to the engine via a recovery tank;
a fuel return line returning part of the fuel from the engine to the recovery tank;
A fuel supply device, wherein an oil removal and recovery device is installed on the fuel return line up to the recovery tank or in the recovery tank.
(Claim 2)
2. The fuel supply system of claim 1, wherein said oil removal and recovery system includes a weir for improving fuel-oil separation and a gauge for determining a fuel-oil interface.
(Claim 3)
3. A fuel supply system according to claim 2, wherein said meter is an electrostatic level switch or a density meter.
(Claim 4)
A gas-liquid separator for introducing the fuel into a fuel return line returning part of the fuel from the engine to the recovery tank and separating it into vaporized ammonia gas, liquefied ammonia and oil,
4. The fuel supply system according to claim 1, further comprising an abatement device for introducing the vaporized ammonia gas and water separated by the gas-liquid separator to generate ammonia water.
(Claim 5)
A fuel supply line for supplying any one fuel selected from liquefied ammonia, liquefied petroleum gas, and methanol to the engine includes a fuel tank, a low-pressure fuel pump, a first buffer tank, and a high-pressure fuel. comprising a pump, a heater or cooler, and a filter;
A recovery tank is provided in a fuel return line that returns part of the fuel from the engine,
Install an oil removal and recovery device in the recovery tank,
A fuel supply device, wherein the oil-free fuel is returned to the first buffer tank.
(Claim 6)
6. The fuel supply system according to claim 5, further comprising a second buffer tank and/or a drain tank for storing the oil separated by the oil removal and recovery device.
(Claim 7)
7. The fuel supply system according to claim 6, wherein a drain room comprising a second buffer tank for recovering residual liquid and/or a drain tank is provided below the fuel supply room in which the fuel supply line is formed.

According to the present invention, it is possible not only to provide a fuel supply system that can use fuel such as liquefied ammonia, liquefied petroleum gas, and methanol, but also to provide a fuel supply system that does not send the returned fuel to the fuel tank. can do.
Further, according to the present invention, it is possible to provide a fuel supply device that can suitably separate the seal oil from the liquefied ammonia fuel or the like even if the return fuel contains the seal oil.

FIG. 1 is a flowchart showing one embodiment of the fuel supply system of the present invention; Schematic cross-sectional view showing an example of a recovery tank applied to the fuel supply system of FIG. Schematic explanatory drawing which shows an example of the gas-liquid separator applied to the fuel supply apparatus of FIG. FIG. 2 is a flowchart showing another form of the fuel supply system of the present invention;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing.

Embodiment 1 of the present invention will be described with reference to FIG.
FIG. 1 is a flow diagram showing one embodiment of the fuel supply system of the present invention.
In FIG. 1, 1 is a marine engine, to which fuel is supplied from a fuel tank 2 through a drain tank 4 . As the ship engine 1, an engine that can handle dual fuel is preferable. For example, an engine that can use a dual fuel that uses two types of fuel, heavy oil and the following fuel, can be exemplified.

Some of the fuels in dual-fuel compatible engines can be fuels such as liquefied ammonia, liquefied petroleum gas (LPG), and methanol. Also, liquefied petroleum gas may be either butane-rich or propane-rich, and either main component can be used. This is because there are very few LPGs that completely contain only butane, and it is conceivable that they may not be completely mixed with the seal oil. In other words, if the amount of propane contained in LPG only changes the degree of dissolution in the seal oil and does not completely dissolve the propane, the seal oil can be separated by the oil removal and recovery device of the present invention.

It should be noted that _NH3 is polar and oil is non-polar, so they do not mix. Similarly, methanol is polar and does not mix with oil.
LPG is classified into LPG whose main component is propane (propane-rich LPG) and LPG whose main component is butane (butane-rich LPG), depending on the production area. It is presumed that the ease of mixing with oil is generally related not only to the evaluation based on polarity and nonpolarity alone, but also to the odd effect and the shortness of the chain length.

Long-chain alkanes with an even number of carbon atoms form a "parallel hexahedron" in which the molecular chain is long in the chain length direction when completely packed (in the crystalline state of a solid). So the packing gets worse. Ease of packing indicates lipophilicity.

In other words, C ₃ H ₈ (propane) has the smallest odd number of 3 carbon atoms, so it is greatly affected by end chipping and is difficult to pack. On the other hand, C ₄ H ₁₀ (butane) has an even number of carbon atoms, 4, and therefore packs well.

The present inventor confirmed by experiments that there is a difference that liquefied C ₄ H ₁₀ dissolves in seal oil and liquefied C ₃ H ₈ does not dissolve in seal oil.

From the above, the fuel stored in the fuel tank 2 of the present invention is any one of fuels selected from liquefied ammonia, liquefied petroleum gas, and methanol, because the fuel supply device of the present invention dissolves in oil. It is particularly useful for fuels that do not dissolve in oil, but even fuels that dissolve in oil can be used, i.e. any fuel such as liquefied ammonia, liquefied petroleum gas and methanol can be used simply by changing the fuel supplied to the fuel tank. It is intended to be a highly versatile fuel supply device that can be used as it is, expanding the range of fuel choices and can be used with a wide variety of fuels.

A case where the fuel of this embodiment is mainly liquefied ammonia will be described below.

As the fuel tank 2, a low-pressure tank such as a full reflex type or a semi-reflex type is used. When surplus ammonia gas is generated, it is preferable to recover it and use it as a reducing agent for the denitrification device. The fuel tank 2 can be provided with a reliquefaction device 2A. In the reliquefying device 2A, ammonia gas discharged as gas from the fuel tank 2 is introduced, pressurized to generate liquefied ammonia, and can be returned to the fuel tank. Further, various ammonia gases such as ammonia gas discharged from the gas-liquid separator 12 (12A, 12B) and ammonia gas obtained by nitrogen purging are introduced into the reliquefying device 2A and pressurized to produce liquefied ammonia. It can also be generated and returned to the fuel tank 2.

Liquefied ammonia, which is fuel filled in the fuel tank 2, is sent to the recovery tank 4 via a low-pressure pump 3, which is a low-pressure fuel pump. The discharge pressure of the low-pressure pump 3 is preferably in the range of 1.8-2.0 MPaG (gauge pressure).

The fuel can be heated by the heater 3A in the process of being sent to the recovery tank 4 . Here, the heater 3A is installed because the fuel may be at a low temperature depending on the type of tank.

In form 1, liquefied ammonia has a fuel supply line from the fuel tank 2 to the engine 1 via the recovery tank 4, and a fuel return line that returns part of the fuel from the engine 1 to the recovery tank 4. ing.

A fuel supply line leading from the recovery tank 4 to the engine 1 is provided with a high pressure pump 5 as a high pressure fuel pump, a heater 5A, a filter 7A or 7B, and an SVT 10 as a fuel valve train (interface).

The fuel in the recovery tank 4 is sent to the heater 5A via the high pressure pump 5. The discharge pressure of the high-pressure pump 5 is preferably in the range of 8.0-8.5 MPaG (gauge pressure). In this embodiment, the discharge pressure when LPG is used as fuel is preferably in the range of 5.0 to 5.5 MPaG, and the discharge pressure when methanol is used as fuel is in the range of 1.0 to 1.5 MPaG. is preferred.

Here, the heater 5A is installed as a backup in case the heater 3A cannot control the temperature, and if it can be controlled by the heater 3A, there is no need to install it.

The fuel is then filtered through filter 7A or filter 7B. Here, the filters 7A and 7B are installed for the purpose of protecting the inside of the engine and valves.

The filters 7A and 7B can remove solid matter and rust contained in the fuel.

The fuel is sent to the engine 1 via the SVT 10 after being filtered by the filter 7A or the filter 7B.

The SVT 10 is a fuel valve train, and includes accessories (high-pressure pump 5, heater 5A, filters 7A and 7B) present in the process of supplying the fuel in the recovery tank 4 to the engine 1 by the high-pressure pump 5, and the engine 1. is an interface between

Nitrogen gas is supplied to the SVT 10 from a nitrogen supply device 10A. Although not shown, nitrogen gas is used for fuel purging in the engine 1, degassing before maintenance, airtightness testing after maintenance, and the like.

The fuel valve train is the interface between the ancillaries and the engine 1, as described above, and its purpose is to safely isolate the engine 1 during shutdown and maintenance, and to maintain the nitrogen supply mentioned above. For example, the nitrogen gas supplied from the device 10A is purged.

In this embodiment, a fuel return line for returning part of the fuel from the engine 1 to the recovery tank 4 is provided. A fuel return line from the engine 1 to the recovery tank 4 is provided with an RVT 11 as a fuel valve train (interface), and a cooler 15 is provided in a system leading to the recovery tank 4 .

In the engine 1, part of the fuel is returned for flow rate adjustment and temperature adjustment. At that time, seal oil is included in part of the fuel. returned. That is, in this embodiment, fuel circulates between the recovery tank 4 and the engine 1 .

According to this aspect, a part of the fuel is returned to the recovery tank 4, and the recovery tank 4 serves as a tank that supplies fuel to the engine. is not contaminated with seal oil.

As shown in FIG. 2, in the recovery tank 4, the fuel returned from the engine 1 and the liquefied ammonia sent from the fuel tank 2 are mixed.

The recovery tank 4 is provided with an oil removal/recovery device configured to separate liquid ammonia and seal oil as shown.

That is, in the case of liquefied ammonia (NH ₃ ), since it does not mix with seal oil, both are separated into layers. The presence of liquefied ammonia can be determined using a density meter or electrostatic level switch.

The density ρ of liquefied ammonia at 25° C. is about 600 kg/m ³ , and the density ρ of seal oil is about 900 kg/m ³ . Therefore, as shown in FIG. Separated into lower layers.

LPG (propane-rich) has a density ρ of about 500 kg/m ³ at 25°C, and LPG (butane-rich) has a density ρ of about 578 kg/m ³ at 25°C. The density ρ of methanol at 20°C is about 792 kg/m ³ . Therefore, since the seal oil has a density ρ of about 900 kg/m ³ , it is possible to separate the fuel into an upper layer and the seal oil into a lower layer as shown in FIG. 2 if the seal oil does not completely dissolve in the oil.

As shown in FIG. 2 , the recovery tank 4 is provided with a barrier plate 40 so that only the liquefied ammonia in the upper layer is sent to the liquefied ammonia tank 41 . The liquefied ammonia in the liquefied ammonia tank 41 is fed as fuel in the direction of the engine 1 by the high-pressure pump 5 .

The lower seal oil is removed by opening the drain valve 42 and stored in the drain tank 43 . This drain valve 42 may control discharge by a signal from a sensor 44 that detects the liquid level of seal oil. By installing the sensor 44, it is possible to check the oil removal state and efficiently discharge the seal oil. This seal oil can also be reused in the present invention.

With such a configuration, the liquefied ammonia fuel from which the seal oil has been separated and removed can be supplied to the engine 1 by the oil removal/recovery device.

In this embodiment, due to the existence of the above-described dam plate 40, the seal oil brought in from the fuel return line can be efficiently separated from the fuel, so that when the fuel from which the seal oil is separated is supplied to the engine again, it is possible to use a filter or the like. Fuel can be efficiently circulated without clogging the strainer.

Furthermore, as the sensor 44, a liquid level sensor that can detect the liquid level was exemplified, but it is not limited to this. Instruments that can Thereby, the seal oil can be discharged more efficiently.

In this embodiment, when the supply of liquefied ammonia gas is started and stopped, the liquefied ammonia remaining in the pipe and containing gas partially vaporized when the pressure is reduced is removed from the gas-liquid separator 12 in order to purge the inside of the system. (12A, 12B) to separate into vaporized gas and liquid.

As the gas-liquid separator 12, as shown in FIG. 1, a gas-liquid separator 12A and a gas-liquid separator 12B can be installed.
Ammonia gas discharged upward from the gas-liquid separators 12A and 12B is sent to the abatement device 13 .
The liquid remaining in the gas-liquid separator 12 is returned to the recovery tank 4 using a pump to recover liquefied ammonia. Nitrogen can also be used to push the liquid out.

The vaporized ammonia gas vaporized by the gas-liquid separator 12 is supplied with water by the abatement device 13 and recovered as aqueous ammonia. The recovered aqueous ammonia can be used, for example, as a reducing agent for a denitrification device on board a ship.

Next, a preferred form of the gas-liquid separator will be described with reference to FIG. The embodiment described below has the effect of reducing the amount of energy to be recovered because the amount of reaction heat is different when ammonia gas is brought into contact with water and when liquefied ammonia and water are brought into contact.

First, fresh water is filled in the gas-liquid separator 12 in advance. Preferably, the gas-liquid separator 12 is provided with a sensor for detecting the liquid level. In the illustrated example, level switches (LS) are provided as the high level sensor 120 and the low level sensor 121 . HH indicates high level and LL indicates low level.

The fresh water valve 122 is opened in advance and fresh water is charged so that the high level sensor 120 detects the HH level and enters the standby state. It is preferable to adjust the amount of fresh water to fill so that the volume of liquefied ammonia (LNH ₃ ) in the fuel supply device is dissolved in water. Also, the fresh water corresponding to the introduced ammonia gas (partly including liquefied ammonia) can be set to an appropriate amount by adjusting the HH level of the liquid level sensor.

Next, the valve 123 shown in FIG. 3 is opened to feed the liquefied ammonia LNH ₃ into the gas-liquid separator 12 to bring the liquefied ammonia and water into contact with each other to form ammonia water.

Liquefied ammonia LNH ₃ is supplied from a fuel return system to recovery tank 4 via RVT 11 . Therefore, in the RVT 11, the liquefied ammonia is depressurized and returned to the recovery tank 4, so a part of it may be vaporized when depressurizing, and the liquefied ammonia LNH ₃ sent to the gas-liquid separator 12 , the case of becoming liquefied ammonia containing partially vaporized ammonia gas.

Next, after the state in which the liquefied ammonia LNH ₃ has completely escaped is detected by, for example, a level switch, a pressure gauge, etc. (not shown) in the fuel supply device, it is recovered as aqueous ammonia in the primary receiving tank 125 via the pump 124 . The aqueous ammonia collected in the primary receiving tank 125 can be reused as fuel by supplying it to the recovery tank 4 as shown in FIG.

Next, the pump 124 extracts the liquid until the liquid level reaches the LL level, and when the low level sensor 121 detects the LL level, the pump 124 is stopped. This completes the series of processes of the gas-liquid separator.

Then, the fresh water valve 122 is opened again, fresh water is introduced, and the high level sensor 120 fills in until the HH level is detected.

Ammonia gas separated above the liquid surface from the gas-liquid separator 12 is sent to the abatement device 13 . Water is supplied to the abatement device 13 to produce aqueous ammonia.

Ammonia water discharged from the abatement device 13 is sent to the SCR 16 and processed/removed by being used as a reducing agent.

According to the apparatus shown in FIG. 3 and the method using the same, there is an effect that the abatement apparatus can be made compact. This is because the amount of ammonia to be removed by the abatement device is reduced. It also has the effect of reducing the amount of reaction heat generated when ammonia and water are brought into contact with each other.

Next, Embodiment 2 of the present invention will be described with reference to FIG.
The fuel supply line in mode 2 is located on the A side of the dashed line in FIG. 4, and is a fuel supply line that supplies any one type of fuel selected from liquefied ammonia, liquefied petroleum gas, and methanol to the engine. .

Equipment provided in the fuel supply line will be described below.
The fuel tank 2 is filled with liquefied ammonia. Liquefied ammonia is supplied to the first buffer tank 20 by the low pressure pump 3 .

A fuel supply line from the first buffer tank 20 to the engine 1 is provided with a high-pressure pump 5, a heater 5A, a filter 7A or 7B, and an SVT 10 as a fuel valve train (interface).

On the other hand, a fuel return line from the engine 1 to the recovery tank 4 located on the B side of the broken line in FIG. 4 is provided with an RVT 11 as a fuel valve train (interface). That is, a recovery tank 4 is provided on a fuel return line for returning part of the fuel from the engine 1 .

Also in this form 2, similarly to the form 1, the recovery tank 4 is provided with an oil removal/recovery device.
Since the structure of this oil removing and recovering device is the same as that described in Embodiment 1, its description is omitted.

The oil (seal oil) separated to the lower layer by the oil removal and recovery device of the recovery tank 4 is transferred to the drain tank 43 via the drain valve 42 and the transfer pump 45 .

The second buffer tank 22 functions as a primary receiving tank for liquefied ammonia when the inner pipe of the double pipe is damaged as a countermeasure against leakage when the pipe is damaged in the engine room. Under normal conditions, air flows from the RVT 11 to the second buffer tank 22 . However, if an abnormality such as pipe breakage occurs, provision of the second buffer tank 22 allows the fuel (liquefied ammonia, etc.) in the engine 1 to be recovered from the RVT 11 . Further, ammonia water, which is fuel in the engine 1, can be supplied to the SCR 16 as a reducing agent via the second buffer tank 22. As a result, the reducing agent can be supplied to the SCR 16 without passing through an abatement device (not shown). As a result, the abatement device can be made compact and the release of ammonia gas into the atmosphere can be suppressed.

In the recovery tank 4 shown in FIG. 4 , the liquefied ammonia fuel in the liquefied ammonia tank 41 is sent to the first buffer tank 20 by the pump 24 . In this case, it is also preferable to provide a check valve (not shown) between the pump 24 and the first buffer tank 20 so that the liquid does not flow from the first buffer tank 20 toward the recovery tank 4 .

Alternatively, the ammonia gas obtained by vaporizing the liquefied ammonia in the recovery tank 4 can be sent to an abatement device (not shown), and ammonia water can be sent to the SCR 16 as a reducing agent via the abatement device.

In this embodiment, a drain room comprising the second buffer tank 22 and/or the drain tank 43 for collecting the residual liquid can be installed below the fuel supply room in which the fuel supply line is formed. By installing it in the lower part in this way, the liquid can be dropped by its own weight, the amount of nitrogen supplied into the fuel supply device can be reduced, and the abatement device can be made compact.

Further, the ammonia gas generated from the fuel tank 2, the recovery tank 4, etc. is treated and removed by generating ammonia water by an abatement device (not shown) and sending it to the SCR 16, where it is used as a reducing agent. be done.

1: Engine 2: Fuel tank 2A: Reliquefaction device 3: Low pressure pump 3A: Heater 4: Recovery tank 40: Dam plate 41: Liquefied ammonia tank 42: Drain valve 43: Drain tank 44: Sensor 45: Transfer pump 5: High pressure Pump 5A: Heater 6: Parallel 7A: Filter 7B: Filter 10A: Nitrogen supply device 12: Gas-liquid separator 12A: Gas-liquid separator 12B: Gas-liquid separator 120: High level sensor 121: Low level sensor 122: Clear water valve 123: valve 124: pump 125: primary receiving tank 13: abatement device 15: cooler 16: SCR
20: first buffer tank 22: second buffer tank 24: transfer pump

(Claim 1)
a fuel supply line from a fuel tank storing any one of fuel selected from liquefied ammonia, liquefied petroleum gas, and methanol to the engine via a recovery tank;
a fuel return line returning part of the fuel from the engine to the recovery tank;
A fuel supply system, wherein an oil removal/recovery device is installed in the recovery tank.
(Claim 2)
2. The fuel supply system of claim 1, wherein said oil removal and recovery system includes a weir for improving fuel-oil separation and a gauge for determining a fuel-oil interface.
(Claim 3)
3. A fuel supply system according to claim 2, wherein said meter is an electrostatic level switch or a density meter.
(Claim 4)
A gas-liquid separator for introducing the fuel into a fuel return line returning part of the fuel from the engine to the recovery tank and separating it into vaporized ammonia gas, liquefied ammonia and oil,
4. The fuel supply system according to claim 1, further comprising an abatement device for introducing the vaporized ammonia gas and water separated by the gas-liquid separator to generate ammonia water.
(Claim 5)
A fuel tank, a low-pressure fuel pump, a first buffer tank, and a high-pressure fuel pump are provided in a fuel supply line for supplying any one of fuel selected from liquefied ammonia, liquefied petroleum gas, and methanol to the engine. , a heater , and a filter,
A recovery tank is provided in a fuel return line that returns part of the fuel from the engine,
Install an oil removal and recovery device in the recovery tank,
A fuel supply device, wherein the oil-free fuel is returned to the first buffer tank.
(Claim 6)
6. The fuel supply device according to claim 5, further comprising a drain tank for storing the oil separated by the oil removal and recovery device.
(Claim 7)
7. The fuel supply system according to claim 6, wherein a drain room having a drain tank for recovering residual liquid is installed below the fuel supply room in which the fuel supply line is formed.

Claims (7)

a fuel supply line from a fuel tank storing any one of fuel selected from liquefied ammonia, liquefied petroleum gas, and methanol to the engine via a recovery tank;
a fuel return line returning part of the fuel from the engine to the recovery tank;
A fuel supply device, wherein an oil removal and recovery device is installed on the fuel return line up to the recovery tank or in the recovery tank. 2. The fuel supply system of claim 1, wherein said oil removal and recovery system includes a weir for improving fuel-oil separation and a gauge for determining a fuel-oil interface. 3. A fuel supply system according to claim 2, wherein said meter is an electrostatic level switch or a density meter. A gas-liquid separator for introducing the fuel into a fuel return line returning part of the fuel from the engine to the recovery tank and separating it into vaporized ammonia gas, liquefied ammonia and oil,
4. The fuel supply system according to claim 1, further comprising an abatement device for introducing the vaporized ammonia gas and water separated by the gas-liquid separator to generate ammonia water. A fuel supply line for supplying any one fuel selected from liquefied ammonia, liquefied petroleum gas, and methanol to the engine includes a fuel tank, a low-pressure fuel pump, a first buffer tank, and a high-pressure fuel. comprising a pump, a heater or cooler, and a filter;
A recovery tank is provided in a fuel return line that returns part of the fuel from the engine,
Install an oil removal and recovery device in the recovery tank,
A fuel supply device, wherein the oil-free fuel is returned to the first buffer tank. 6. The fuel supply system according to claim 5, further comprising a second buffer tank and/or a drain tank for storing the oil separated by the oil removal and recovery device. 7. The fuel supply system according to claim 6, wherein a drain room comprising a second buffer tank for recovering residual liquid and/or a drain tank is provided below the fuel supply room in which the fuel supply line is formed.

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