WO2019008923A1

WO2019008923A1 - Ship

Info

Publication number: WO2019008923A1
Application number: PCT/JP2018/019409
Authority: WO
Inventors: 義浩岡田; 和也萩原; 輝久古賀; 雄輝宍粟; 岳夫宇井; 俊宏 ▲高▼木; 宏之武田; 尚子印藤
Original assignee: 川崎重工業株式会社
Priority date: 2017-07-05
Filing date: 2018-05-18
Publication date: 2019-01-10
Also published as: CN110831850A; JP6901919B2; KR20200021091A; SG11201913142XA; KR102330773B1; CN110831850B; JP2019014335A

Abstract

This ship comprises: a fuel tank which retains LPG; a propulsion engine which uses the LPG as fuel; a fuel supply line which supplies the LPG from the fuel tank to the engine and is provided with a first cutoff valve; a fuel recovery line which collects unused LPG from the engine for recovery to the fuel tank and is provided with a second cutoff valve; a first purge line which is located between an engine room and the second shutoff valve so as to supply inert gas to the fuel recovery line; and a purge tank which is connected to the fuel supply line between the engine room and the first cutoff valve by a second purge line provided with a third cutoff valve. The second purge line and the purge tank are arranged in the portion of the fuel supply line within the engine room and below the portion of the fuel recovery line within the engine room.

Description

Ship

The present invention relates to a ship including a propulsion engine fueled by LPG.

In conventional vessels, the fuel for the propulsion engine is generally a fuel oil such as heavy oil or LNG (Liquefied Natural Gas). In recent years, it has also been proposed to use LPG (Liquefied Petroleum Gas) as fuel for a propulsion engine.

For example, Patent Document 1 discloses a ship for supplying LPG in liquid form from a fuel tank to a propulsion engine. When LPG is used as a fuel, there is no need to take measures against sulfur oxides compared to fuel oil and there is an advantage that carbon dioxide emissions are small, and the specific gravity is large compared to LNG, so the fuel tank can be miniaturized. There is a merit that.

Korean Published Patent No. 2012-0113398

When using LPG as fuel, connect the fuel tank and the propulsion engine with the fuel supply line and the fuel recovery line, and use only the necessary amount in the engine while circulating LPG between the fuel tank and the engine Conceivable.

By the way, when a low boiling point fuel such as LNG or LPG is used as the fuel for the propulsion engine, it is general to purge the fuel piping in the engine room with an inert gas when the fuel is not used or in an emergency It is necessary for However, in the configuration using the fuel supply line and the fuel recovery line as described above, it is difficult to expel the liquid LPG out of the engine room by the supply of the inert gas.

Then, an object of this invention is to provide the ship which can purge easily the part which exists in the engine room in the fuel supply line through which LPG flows, and a fuel collection | recovery line by inert gas.

In order to solve the above problems, the ship according to the present invention is provided with a fuel tank storing LPG, a propulsion engine disposed in an engine room using LPG as a fuel, and LPG supplied from the fuel tank to the engine A fuel supply line provided with a first shutoff valve outside the engine compartment, and a fuel shutoff valve provided outside the engine compartment for recovering unused LPG from the engine to the fuel tank The engine room by a line, a first purge line for supplying an inert gas to the fuel recovery line between the engine compartment and the second shutoff valve, and a second purge line provided with a third shutoff valve; A purge tank connected to the fuel supply line with the first shutoff valve, the second purge line and the purge tank Than the portion present in the engine room in the engine lies in the room portion and said fuel return line in the supply line is disposed below, and wherein the.

According to the above configuration, the second purge line and the purge tank are disposed below the portions of the fuel supply line and the fuel recovery line existing in the engine room. Therefore, when the fuel supply line and the portion in the engine room in the fuel recovery line are purged with the inert gas, the first shutoff valve and the second shutoff valve are closed to open the third shutoff valve, and the first purge If inert gas is supplied to the fuel recovery line through the line, gravity can be used to expel the LPG from the fuel supply line into the purge tank. Therefore, the fuel supply line through which the LPG flows and the portion of the fuel recovery line existing in the engine room can be easily purged with the inert gas.

The portion of the fuel supply line existing in the engine room may be an upward slope toward the engine, and the portion of the fuel recovery line existing in the engine room may be a downward slope toward the engine . According to this configuration, the fuel supply line and the portion of the fuel recovery line existing in the engine room can be more easily purged with the inert gas.

The above ship further includes a heater for heating LPG supplied to the fuel tank to 0 ° C. or higher, and the fuel tank holds the LPG at a pressure higher than the saturated vapor pressure at the temperature in the fuel tank. May be According to this configuration, the fuel tank and the pipes constituting the fuel supply line and the fuel recovery line can be formed not from low-temperature steel such as nickel-based alloy but from general steel, so cost can be reduced. .

The fuel recovery line may be provided with a cooler for cooling the LPG to a predetermined temperature. According to this configuration, it is possible to suppress flash (rapid vaporization) of the recovered LPG in the fuel tank.

The fuel recovery line is provided with a pressure regulating valve, which assumes the pressure of the LPG upstream of the pressure regulating valve at the saturated steam pressure or the temperature of the LPG at the outlet of the engine. It may be adjusted to be higher than the saturated vapor pressure at the maximum temperature. According to this configuration, it is possible to prevent the LPG from flushing in the fuel recovery line.

The fuel tank may include a storage tank into which LPG is introduced, and a service tank connected to the engine by the fuel supply line and the fuel recovery line, to which the LPG is supplied from the storage tank. According to this configuration, the fuel tank can be divided into a storage tank for introducing LPG and a service tank for circulating LPG.

An inert gas may be introduced into the service tank. According to this configuration, the holding pressure of the service tank can be made higher than the saturated steam pressure, and it becomes easy to secure the necessary effective suction head (NPSHr) of the pump that supplies LPG to the engine.

The purge tank is connected to the fuel tank by a return line provided with a fourth shut-off valve, and the above-mentioned vessel includes the first shut-off valve, the second shut-off valve, the third shut-off valve, and the third (4) The control device for controlling the shutoff valve, which is used to circulate the LPG between the fuel tank and the engine through the fuel supply line and the fuel recovery line, the third shutoff valve With closing, the first shut-off valve and the second shut-off valve are opened, and a purge operation is performed to purge the portion existing in the engine room in the fuel supply line and the portion existing in the engine room in the fuel recovery line While closing the first shut-off valve, the second shut-off valve, and the fourth shut-off valve, and opening the third shut-off valve, It may open the fourth shut-off valve after the di operation is completed. According to this configuration, after completion of the purge operation, the pressure of the inert gas can be used to return the LPG accumulated in the purge tank to the fuel tank through the return line.

For example, the above ship further includes a pressure gauge for detecting the pressure of the purge tank, and a control device for controlling the first shutoff valve, the second shutoff valve, and the third shutoff valve, and the control device When the pressure of the purge tank detected by the pressure gauge becomes equal to or higher than a predetermined value, it may be determined that the purge operation is completed.

According to the present invention, the fuel supply line through which LPG flows and the portion of the fuel recovery line existing in the engine room can be easily purged with inert gas.

It is a schematic block diagram of the ship concerning one embodiment of the present invention.

FIG. 1 shows a ship 1 according to an embodiment of the present invention. The ship 1 includes a propulsion engine 12 that uses LPG as a fuel, and a fuel tank 2 that stores LPG. The main component of LPG may be propane (propane gas) or butane (butane gas).

In the ship 1, an engine room 11, a relatively narrow first equipment room 14, and a relatively wide second equipment room 15 are formed. The propulsion engine 12 is disposed in the engine room 11. Further, in the engine room 11, a boiler 13 is also disposed, which burns PG gasified by LPG. For example, the propulsion engine 12 is a diesel cycle or Otto cycle reciprocating engine. The second device room 15 does not necessarily have to be a sealed space, and may be an open space (open space).

In the present embodiment, the fuel tank 2 has a relatively large volume of storage tank 21 disposed outside all the

rooms

11, 14, 15 and a relatively small volume disposed in the second equipment room 15. And the service tank 22 of FIG. The storage tank 21 and the service tank 22 are connected to each other by a relay line 26.

The LPG is introduced into the storage tank 21 from the LPG supply source through the fuel introduction line 23. The LPG supply source may be a cargo tank mounted on the ship 1, or may be an LPG supply facility on land or an LPG fuel supply ship.

In the present embodiment, the storage tank 21 is not provided with a device for adjusting the temperature, and the temperature of the storage tank 21 changes in accordance with the atmospheric temperature. On the other hand, LPG introduced from an LPG source is often at about -42 ° C. Therefore, the fuel introduction line 23 is provided with a heater 24 for heating LPG to 0 ° C. or higher. Then, the storage tank 21 holds the LPG at a pressure higher than the saturated vapor pressure at the temperature in the storage tank 21. However, if the LPG supply facility on the land that is the LPG supply source and the LPG fuel supply ship are equipped with a heater, and the temperature of the LPG delivered to the ship 1 is 0 ° C. or higher, the heater 24 is unnecessary. .

The holding pressure of the storage tank 21 refers to the pressure of the gas phase in the storage tank 21 (the holding pressure of the service tank 22 described later is the same). If no gas other than PG is mixed in the storage tank 21, the holding pressure of the storage tank 21 becomes equal to the saturated vapor pressure of the LPG.

For example, when the temperature in the storage tank 21 is 25 ° C., the holding pressure (saturated vapor pressure) of the storage tank 21 is about 1.0 MPa in absolute pressure. Hereinafter, the expression of pressure is absolute pressure unless otherwise specified. Since the saturated vapor pressure of LPG is about 1.8 MPa at 50 ° C., the storage tank 21 is configured to withstand up to, for example, 1.9 MPa.

A pump 25 is installed inside the storage tank 21. The number of pumps 25 may be one or more. The upstream end of the relay line 26 described above is connected to the pump 25. Further, the downstream end of the relay line 26 opens in the service tank 22. Then, the LPG is supplied from the storage tank 21 to the service tank 22 through the relay line 26 by the pump 25. However, the pump 25 may be provided in the middle of the relay line 26 outside the storage tank 21.

Similar to the storage tank 21, the service tank 22 is not provided with a device for adjusting the temperature, and the temperature of the service tank 22 changes following the atmospheric temperature. The service tank 22 holds the LPG at a pressure higher than the saturated vapor pressure at the temperature in the service tank 22.

In the present embodiment, the service tank 22 is connected to an inert gas supply source (not shown) by the inert gas introduction line 54. The inert gas supply source is disposed, for example, in the engine room 11. When the inert gas (for example, nitrogen) is introduced into the service tank 22 through the inert gas introduction line 54, the holding pressure of the service tank 22 becomes higher than the saturated vapor pressure. However, when there is no inert gas in the service tank 22, the holding pressure of the service tank 22 is equal to the saturated vapor pressure of LPG.

At the time of circulation of LPG between the engine 12 and the service tank 22 as described later, the temperature of the service tank 22 may be higher than the atmospheric temperature. For example, when the temperature in the service tank 22 is 40 ° C., the holding pressure (saturated vapor pressure) of the service tank 22 is about 1.45 MPa. The service tank 22 is configured to withstand, for example, 2.0 MPa.

A shutoff valve 55 and a pressure control valve 56 are provided in the inert gas introduction line 54 sequentially from the upstream side. For example, the pressure of the inert gas source described above is 3.0 MPa. The shutoff valve 55 and the pressure regulating valve 56 are controlled by the controller 8. However, in FIG. 1, only some signal lines are drawn for simplification of the drawing. The control device 8 is, for example, a computer having a memory such as a ROM or a RAM and a CPU, and a program stored in the ROM is executed by the CPU.

The control device 8 is electrically connected to a pressure gauge 91 that detects the pressure (holding pressure) of the gas phase in the service tank 22. Then, the control device 8 controls the shutoff valve 55 and the pressure adjustment valve 56 so that the pressure detected by the pressure gauge 91 does not fall below the lower limit of the allowable range.

Furthermore, the service tank 22 is connected to the above-described boiler 13 by a combustion line 73. The upstream end of the combustion line 73 is connected to the top of the service tank 22. In the combustion line 73, a pressure control valve 74 and a heater 75 are provided in this order from the upstream side. The heater 75 heats the mixed gas of the vaporized PG and the inert gas to a temperature suitable for combustion in the boiler 13.

The pressure control valve 74 is controlled by the controller 8. The controller 8 controls the pressure control valve 74 so that the pressure detected by the pressure gauge 91 does not exceed the upper limit of the allowable range. Although not shown, the combustion line 73 is also provided with a pressure control valve for reducing the pressure of the mixed gas supplied to the boiler 13 to 1.0 MPa or less.

The service tank 22 is connected to the propulsion engine 12 by a fuel supply line 31 and a fuel recovery line 41. That is, LPG is supplied from the service tank 22 to the engine 12 through the fuel supply line 31, and unused LPG is recovered from the engine 12 to the service tank 22 through the fuel recovery line 41. In other words, LPG circulates between the service tank 22 and the engine 12 through the fuel supply line 31 and the fuel recovery line 41.

The upstream end of the fuel supply line 31 is connected to the lower part of the service tank 22. On the other hand, a portion (hereinafter referred to as an extended portion in the engine room) 31 a in the engine room 11 of the fuel supply line 31 has an upward slope toward the engine 12.

The fuel supply line 31 is provided with a pump 32, a heater 33, and a shutoff valve 34 (corresponding to a first shutoff valve of the present invention) sequentially from the upstream side. These devices 32 to 34 are disposed outside the engine room 11. More specifically, the pump 32 and the heater 33 are disposed in the second equipment room 15, and the shutoff valve 34 is disposed in the first equipment room 14. The heater 33 heats the LPG to the required temperature (for example, 45 ° C.) of the engine 12.

The shutoff valve 34 is controlled by the controller 8. The control of the shutoff valve 34 will be described in detail later.

The downstream end of the fuel recovery line 41 opens in the service tank 22. On the other hand, a portion (hereinafter referred to as an in-engine-room extended portion) 41 a existing in the engine room 11 in the fuel recovery line 41 has a downward slope toward the engine 12.

In the fuel recovery line 41, the first pressure regulating valve 42, the shutoff valve 43 (corresponding to the second shutoff valve of the present invention), the cooler 44 and the second pressure regulation valve 45 (the pressure regulation of the present invention) (Equivalent to a valve) is provided. These devices 42 to 45 are disposed outside the engine room 11. More specifically, the first pressure regulating valve 42 and the shutoff valve 43 are disposed in the first equipment room 14, and the cooler 44 and the second pressure regulating valve 45 are disposed in the second equipment room 15. The cooler 44 cools the LPG to a predetermined temperature (for example, 40 ° C.).

The first pressure regulating valve 42, the shutoff valve 43 and the second pressure regulating valve 45 are controlled by the controller 8. The control of the shutoff valve 43 will be described in detail later. The control device 8 is electrically connected to a pressure gauge 92 that detects the pressure of the LPG at the inlet of the engine 12 and a pressure gauge 93 that detects the pressure of the LPG upstream of the second pressure regulating valve 45. In the present embodiment, the pressure gauge 93 is located downstream of the cooler 44, but the pressure gauge 93 may be located upstream of the cooler 44.

With regard to the first pressure regulating valve 42, the controller 8 controls the first pressure regulating valve 42 such that the pressure detected by the pressure gauge 92 becomes the required pressure of the engine 12. On the other hand, with regard to the second pressure regulating valve 45, the temperature of the LPG rises a little as the LPG passes through the engine 12 (for example, 55 ° C.). Therefore, as a setting value for control of the second pressure adjusting valve 45, a setting value to be a saturated vapor pressure at the assumed maximum temperature is determined (for example, 2.0 MPa), and the control device 8 The second pressure control valve 45 is controlled such that the pressure detected at step S.2 is higher than the set value.

Alternatively, the controller 8 is electrically connected to a thermometer 81 that detects the temperature of the LPG at the outlet of the engine 12, and the pressure detected by the pressure gauge 93 is the temperature detected by the thermometer 81. The second pressure control valve 45 may be controlled to be higher than the saturated steam pressure of

In the present embodiment, the portion between the heater 33 and the first shutoff valve 34 in the fuel supply line 31 is connected to the portion between the shutoff valve 43 and the cooler 44 in the fuel recovery line 41 by the bypass line 16. ing. The bypass line 16 is provided with a flow control valve 17. The flow control valve 17 is controlled by the controller 8 such that LPG passing through the engine 12 has a predetermined flow rate.

Furthermore, the ship 1 includes a first purge line 51 as a configuration for purging the in-engine room extension 31a of the fuel supply line 31 and the in-engine room extension 41a of the fuel recovery line 41 with an inert gas. A second purge line 61 and a purge tank 6 are provided.

The first purge line 51 connects a portion between the engine compartment 11 and the first pressure control valve 42 in the fuel recovery line 41 with the inert gas supply source described above. That is, the inert gas is supplied to the fuel recovery line 41 between the engine compartment 11 and the first pressure control valve 42 through the first purge line 51. The first purge line 51 is provided with a shutoff valve 52 and a flow control device in order from the upstream side. The flow control device is the flow control valve 53 in the present embodiment, but may be an orifice or the like.

The second purge line 61 connects a portion of the fuel supply line 31 between the shutoff valve 34 and the engine compartment 11 with the purge tank 6. The downstream end of the second purge line 61 is open in the purge tank 6. The second purge line 61 is provided with a shutoff valve 62 (corresponding to a third shutoff valve of the present invention).

The second purge line 61 and the purge tank 6 are disposed below the in-engine room extension 31a of the fuel supply line 31 and the in-room extension 41a of the fuel recovery line 41 in the first equipment room 14. ing.

Furthermore, the purge tank 6 is connected to the service tank 22 by a return line 63 and is connected to the above-described boiler 13 by a combustion line 71. The return line 63 is for returning the liquid LPG to the service tank 22, and the combustion line 71 is for introducing a mixed gas of the vaporized PG and the inert gas to the boiler 13.

The upstream end of the return line 63 is open in the purge tank 6, and the downstream end of the return line 63 is open in the service tank 22. The return line 63 is provided with a shutoff valve 64 (corresponding to a fourth shutoff valve of the present invention).

The upstream end of the combustion line 71 is connected to the top of the purge tank 6. The combustion line 71 is provided with a shutoff valve 72. Although not shown, the combustion line 71 is also provided with a pressure control valve for reducing the pressure of the mixed gas supplied to the boiler 13 to 1.0 MPa or less.

The

shutoff valves

52, 62, 64, 72 and the flow control valve 53 described above are controlled by the controller 8. Hereinafter, control of these valves will be described including control of the shutoff valve 34 of the fuel supply line 31 and the shutoff valve 43 of the fuel recovery line 41.

When circulating LPG between the service tank 22 and the engine 12 through the fuel supply line 31 and the fuel recovery line 41, the controller 8 shuts off the shutoff valve 52 of the first purge line 51 and the second purge line 61. The valve 62, the shutoff valve 64 of the return line 63, and the shutoff valve 72 of the combustion line 71 are closed, and the shutoff valve 34 of the fuel supply line 31 and the shutoff valve 43 of the fuel recovery line 41 are opened. Thus, LPG circulates through the fuel supply line 31 and the fuel recovery line 41.

On the other hand, when performing a purge operation to purge the engine room extension 31 a of the fuel supply line 31 and the engine room extension 41 a of the fuel recovery line 41 with the inert gas, the controller 8 controls the fuel supply line 31. The first shutoff valve 34 and the shutoff valve 43 of the fuel recovery line 41 are closed, and the shutoff valve 52 of the first purge line 51 and the shutoff valve 62 of the second purge line 61 are opened. At this time, the shutoff valve 64 of the return line 63 and the shutoff valve 72 of the combustion line 71 remain closed.

As a result, while the inert gas is supplied to the fuel recovery line 41, the upstream portion including the in-engine room extension portion 41a of the fuel recovery line 41 and the downstream side including the in-engine room extension portion 31a of the fuel supply line 31. The LPG present in the portion is expelled into the purge tank 6. Along with this, the pressure of the purge tank 6 gradually rises. At this time, the control device 8 controls the flow control valve 53 to adjust the flow rate of the inert gas.

The pressure of the purge tank 6 depends on the passing amount of the inert gas in the engine room extension portion 41 a of the fuel recovery line 41 and the engine room extension portion 31 a of the fuel supply line 31.

Therefore, when the pressure detected by the pressure gauge 94 becomes equal to or higher than a predetermined value (purge completion pressure: for example, 1.9 MPa) corresponding to the amount of inert gas to flow, the control device 8 performs the purge operation. Determine that it is complete. In addition, when the pressure required for returning LPG from the purge tank 6 to the service tank 22 (LPG return required pressure: for example, 2.0 MPa in gauge pressure) is higher than the purge completion pressure, the control device 8 further The shutoff valve 52 of the first purge line 51 and the shutoff valve 62 of the second purge line 61 are kept open so that the purge tank 6 is continuously pressurized. Then, when the pressure of the purge tank 6 becomes equal to or higher than the LPG return necessary pressure, the control device 8 closes the shutoff valve 52 of the first purge line 51 and the shutoff valve 62 of the second purge line 61 and thereafter returns the return line. Open the shutoff valve 64 of 63. As a result, after completion of the purge operation, the LPG accumulated in the purge tank 6 can be returned to the service tank 22 through the return line 63 using the pressure of the inert gas.

When the return of the LPG to the service tank 22 is completed, the control device 8 closes the shutoff valve 64 of the return line 63 and opens the shutoff valve 72 of the combustion line 71 to leave the PG and inert gas remaining in the purge tank 6. Mixed gas is supplied to the boiler 13.

As described above, in the ship 1 according to the present embodiment, the second purge line 61 and the purge tank 6 are located in the engine room extension 31 a of the fuel supply line 31 and the engine room extension 41 a of the fuel recovery line 41. Are also located below. Therefore, when purging the engine room extension part 41a of the fuel recovery line 41 and the engine compartment extension part 31a of the fuel supply line 31 with inert gas, LPG is taken from the fuel supply line 31 using gravity. The inside of the purge tank 6 can be expelled. Therefore, the in-engine room extending portion 41a of the fuel recovery line 41 and the in-engine room extending portion 31a of the fuel supply line 31 can be easily purged with the inert gas.

Further, in the present embodiment, since the LPG introduced into the storage tank 21 is heated to 0 ° C. or more by the heater 24, the storage tank 21, the service tank 22, the fuel supply line 31, and the fuel recovery line 41 are configured. Piping can be comprised with common steel materials instead of low temperature steel materials, such as a nickel base alloy. Therefore, the cost can be reduced.

Furthermore, in the present embodiment, since the cooler 44 is provided in the fuel recovery line 41, it is possible to suppress the flash (vaporization) of the recovered LPG in the service tank 22.

Further, in the present embodiment, the pressure of the LPG on the upstream side of the second pressure regulating valve 45 is adjusted by the second pressure regulating valve 45 of the fuel recovery line 41 to be higher than the saturated vapor pressure at the assumed maximum temperature. Therefore, it is possible to prevent the LPG from flushing in the fuel recovery line 41 (in the present embodiment, before the LPG is cooled by the cooler 44).

(Modification)
The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present invention.

For example, when the return line 63 is provided with a check valve, the shutoff valve 64 may not be closed when circulating the LPG between the service tank 22 and the engine 12.

Moreover, in the said embodiment, although the fuel tank 2 was comprised with the storage tank 21 and the service tank 22, the storage tank 21 may be abbreviate | omitted and the fuel tank 2 may be comprised only with the service tank 22. FIG. However, if it is a structure like the said embodiment, the fuel tank 2 can be divided into the storage tank 21 for LPG introduction, and the service tank 22 for LPG circulation.

Further, the in-engine room extension 31a of the fuel supply line 31 does not necessarily have to be an upward slope toward the engine 12, and may be arranged on a horizontal surface. Similarly, the in-engine room extension portion 41a of the fuel recovery line 41 does not necessarily have to be a downward slope toward the engine 12, and may be routed on a horizontal surface. However, with the configuration as in the above embodiment, it is possible to more easily purge the in-engine room extension portion 41a of the fuel recovery line 41 and the in-room portion 31a of the fuel supply line 31 with inert gas. it can.

In addition, the inert gas does not necessarily have to be introduced into the service tank 22, and the holding pressure of the service tank 22 may be equal to the saturated vapor pressure of the LPG. However, with the configuration as in the above embodiment, the holding pressure of the service tank 22 can be made higher than the saturated steam pressure, and securing of the necessary effective suction head (NPSHr) of the pump 32 that supplies the LPG to the engine 12 Becomes easier.

Further, the shutoff valve 72 of the combustion line 71 may be omitted, and the pressure regulating valve (not shown) of the combustion line 71 may be fully closed until the return of the LPG from the purge tank 6 to the service tank 22 is completed.

Further, the return line 63 may be omitted, and after the completion of the purge operation, the entire amount of LPG accumulated in the purge tank 6 may be supplied to the boiler 13 through the combustion line 71 while being vaporized.

Reference Signs List 1 ship 11 engine room 12 engine for propulsion 2 fuel tank 21 storage tank 22 service tank 24 heater 25 pump 31 fuel supply line 31a extension in engine room 34 shutoff valve (first shutoff valve)
41 fuel recovery line 41a engine compartment extension 43 shut-off valve (second shut-off valve)
51 first purge line 6 purge tank 61 second purge line 62 shutoff valve (third shutoff valve)
63 Return line 64 shutoff valve (4th shutoff valve)
8 Controller

Claims

A fuel tank for storing LPG,
A propulsion engine located in the engine room, fueled by LPG,
A fuel supply line for supplying LPG from the fuel tank to the engine, wherein a first shutoff valve is provided outside the engine room;
A fuel recovery line provided with a second shutoff valve outside the engine compartment for recovering unused LPG from the engine to the fuel tank;
A first purge line for supplying an inert gas to the fuel recovery line between the engine compartment and the second shutoff valve;
A purge tank connected to the fuel supply line between the engine compartment and the first shutoff valve by a second purge line provided with a third shutoff valve;
The second purge line and the purge tank are disposed below a portion of the fuel supply line existing in the engine room and a portion of the fuel recovery line existing in the engine room.
The portion of the fuel supply line present in the engine room is uphill towards the engine,
The vessel according to claim 1, wherein a portion of the fuel recovery line existing in the engine room is a down slope toward the engine.
It further comprises a heater for heating LPG supplied to the fuel tank to 0 ° C. or higher,
The ship according to claim 1, wherein the fuel tank holds the LPG at a pressure equal to or higher than a saturated vapor pressure at a temperature in the fuel tank.
The ship according to any one of claims 1 to 3, wherein the fuel recovery line is provided with a cooler for cooling the LPG to a predetermined temperature.
The fuel recovery line is provided with a pressure regulating valve, which assumes the pressure of the LPG upstream of the pressure regulating valve at the saturated steam pressure or the temperature of the LPG at the outlet of the engine. The vessel according to any one of claims 1 to 4, wherein the pressure is adjusted to be higher than the saturated steam pressure at the maximum temperature.
The fuel tank may include a storage tank into which LPG is introduced, and a service tank connected to the engine by the fuel supply line and the fuel recovery line to which LPG is supplied from the storage tank. The ship according to any one of the preceding claims.
The vessel according to claim 6, wherein an inert gas is introduced into the service tank.
The purge tank is connected to the fuel tank by a return line provided with a fourth shutoff valve.
The control device further controls the first shutoff valve, the second shutoff valve, the third shutoff valve, and the fourth shutoff valve.
The control device closes the third shutoff valve and circulates the first shutoff valve and the second shutoff valve when circulating LPG between the fuel tank and the engine through the fuel supply line and the fuel recovery line. When performing a purge operation in which a valve is opened and a portion existing in the engine room in the fuel supply line and a portion existing in the engine room in the fuel recovery line are purged with an inert gas, the first shutoff valve The ship according to any one of claims 1 to 7, wherein the second shutoff valve and the fourth shutoff valve are closed and the third shutoff valve is opened, and the fourth shutoff valve is opened after the purge operation is completed. .
A pressure gauge for detecting the pressure of the purge tank;
The control device further controls the first shutoff valve, the second shutoff valve, and the third shutoff valve.
The control device according to any one of claims 1 to 8, wherein when the pressure of the purge tank detected by the pressure gauge exceeds a predetermined value, the control device determines that the purge operation is completed. Ship.