KR20200021091A - Ship - Google Patents

Abstract

The vessel includes a fuel tank for storing LPG, a propulsion engine disposed in an engine room using LPG as a fuel, a fuel supply line for supplying LPG to the engine from the fuel tank and provided with a first shutoff valve, and a fuel tank from the engine. A fuel recovery line for recovering unused LPG and a second shutoff valve, a first purge line for supplying an inert gas to the fuel recovery line between the engine room and the second shutoff valve, and a third shutoff valve. A purge tank connected by a purge line to the fuel supply line between the engine room and the first shut-off valve, wherein the second purge line and the purge tank are located in the engine room at the fuel supply line and in the fuel recovery line It is arrange | positioned below the part which exists in a room.

Description

Ship

The present invention relates to a ship comprising a propulsion engine using LPG as fuel.

In conventional vessels, the fuel of a propulsion engine is generally fuel oil such as heavy oil or LNG (Liquefied Natural Gas). Recently, LPG (Liquefied Petroleum Gas) has also been proposed as a fuel for propulsion engines.

For example, Patent Document 1 discloses a vessel in which LPG is supplied as a liquid to a propulsion engine from a fuel tank. In the case of using LPG as a fuel, there is an advantage in that sulfur oxides are not required as compared to fuel oil, and carbon dioxide emission is low.

Korean Laid-Open Patent Publication No. 2012-0113398

In the case of using LPG as fuel, it is considered to connect the fuel tank and the propulsion engine to the fuel supply line and the fuel recovery line, and to use only the necessary amount in the engine while circulating the LPG between the fuel tank and the engine.

However, when using low boiling point fuel such as LNG or LPG as the fuel of the propulsion engine, it is common to purge the fuel pipe in the engine room with inert gas when the fuel is not used and in an emergency. As needed. However, in the above-described configuration using the fuel supply line and the fuel recovery line, it is difficult to drive LPG, which is a liquid, out of the engine room by supplying inert gas.

Accordingly, an object of the present invention is to provide a vessel capable of easily purging a portion existing in an engine room with an inert gas in a fuel supply line and a fuel recovery line through which LPG flows.

In order to solve the said subject, the ship which concerns on this invention is a fuel tank which stores LPG, the propulsion engine arrange | positioned in the engine room which uses LPG as fuel, and supplies the LPG to the said engine from the said fuel tank, and said engine A fuel supply line provided with a first shutoff valve outside the room, an LPG unused from the engine as the fuel tank, and a fuel recovery line provided with a second shutoff valve outside the engine room, the engine room and the second shutoff A purge connected between the engine room and the first shutoff valve by a first purge line supplying an inert gas to the fuel recovery line between the valves and a second purge line provided with a third shutoff valve; A tank, said second purge line and said purge tank being in said engine room at said fuel supply line and said fuel In the number of lines it is characterized in that arranged on the lower side than the portion present in the engine room.

According to the above configuration, the second purge line and the purge tank are disposed below the portion present in the engine room of the fuel supply line and the fuel recovery line. Therefore, when purging the portion of the fuel supply line and the fuel recovery line in the engine room with inert gas, the first purge line is closed while the first shutoff valve and the second shutoff valve are closed. Feeding the inert gas to the fuel recovery line via this allows gravity to drive the LPG from the fuel supply line into the purge tank. Therefore, the portion present in the engine room of the fuel supply line and the fuel recovery line through which the LPG flows can be easily purged with inert gas.

A portion present in the engine room in the fuel supply line is formed uphill toward the engine (formed as an upward gradient), and a portion present in the engine room in the fuel recovery line is formed downhill toward the engine (downward) Gradient). According to this configuration, the portion present in the engine room in the fuel supply line and the fuel recovery line can be more easily purged with inert gas.

The vessel may further include a heater for heating the LPG supplied to the fuel tank to 0 ° C or higher, and the fuel tank may maintain the LPG at a pressure equal to or higher than the saturated vapor pressure at the temperature of the fuel tank. According to such a structure, since the fuel tank and the piping which comprise a fuel supply line and a fuel recovery line can be comprised with general steel rather than low temperature steel, such as nickel alloy, cost can be saved.

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 the recovered LPG from flashing (rapid vaporization) in the fuel tank.

The fuel recovery line is provided with a pressure regulating valve, the pressure regulating valve being a maximum of the saturated steam pressure at the temperature of the LPG at the outlet of the engine or assumed maximum LPG pressure upstream of the pressure regulating valve. You may adjust so that it may be higher than saturated steam pressure in temperature. According to this configuration, it is possible to prevent the LPG from flashing in the fuel recovery line.

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

Inert gas may be introduced into the service tank. According to such a structure, the holding pressure of a service tank can be made higher than saturated steam pressure, and it becomes easy to ensure the required effective suction head NPSHr of the pump supplied to an LPG engine.

The purge tank is connected to the fuel tank through a transfer line provided with a fourth shutoff valve, and the vessel controls the first shutoff valve, the second shutoff valve, the third shutoff valve, and the fourth shutoff valve. And a control device, wherein the control device closes the third shut-off valve and simultaneously closes the third shut-off valve when the LPG is circulated between the fuel tank and the engine via the fuel supply line and the fuel recovery line. When the shutoff valve and the second shutoff valve are opened and a purge operation is performed to purge 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 with inert gas. Closing the first shutoff valve, the second shutoff valve and the fourth shutoff valve and simultaneously opening the third shutoff valve; After the operation is completed may be opened and the fourth shut-off valve. According to this configuration, after the purge operation is completed, the LPG accumulated in the purge tank can be returned to the fuel tank through the transfer line by using the pressure of the inert gas.

For example, the 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. May determine that the purge operation is completed when the pressure of the purge tank detected by the pressure gauge reaches a predetermined value or more.

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

1 is a schematic configuration diagram of a ship according to an embodiment of the present invention.

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

The ship 1 is provided with an engine room 11, a relatively narrow first device room 14, and a relatively wide second device room 15. The propulsion engine 12 is disposed in the engine room 11. In addition, in the engine room 11, the boiler 13 which burns PG vaporized by LPG is also arrange | positioned. For example, the propulsion engine 12 is a reciprocating engine of a diesel cycle or an auto cycle. Here, the second device room 15 does not necessarily need to be a closed space, but may be an open space (open space).

According to the present embodiment, the fuel tank 2 has a relatively large volume storage tank 21 disposed outside of all the rooms 11, 14, 15, and a relatively small volume disposed within the second equipment room 15. It consists of the service tank 22 of the. The storage tank 21 and the service tank 22 are connected to each other by the relay line 26.

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

According to this embodiment, the apparatus for adjusting the temperature is not provided in the storage tank 21, 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 about -42 ° C. Therefore, the fuel introduction line 23 is provided with the heater 24 which heats LPG to 0 degreeC or more. The storage tank 21 maintains the LPG at a pressure equal to or higher than the saturated vapor pressure at the temperature in the storage tank 21. However, since the heater is installed in the LPG supply facility and the LPG fuel supply line of the LPG supply source, the heater 24 is unnecessary if the temperature of the LPG delivered to the vessel 1 is 0 ° C or more.

Here, the holding pressure of the storage tank 21 means the pressure of the gas phase in the storage tank 21 (the same holds for the holding pressure of the service tank 22 described later). If no gas other than PG is mixed in the storage tank 21, the holding pressure of the storage tank 21 is 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 at absolute pressure. Below, the indication of pressure is absolute pressure except the case where there is particular notice. Here, since the saturated vapor pressure of the LPG is about 1.8 MPa at 50 ° C., the storage tank 21 is configured to withstand up to 1.9 MPa, for example.

The pump 25 is provided in the storage tank 21. The number of pumps 25 may be one or plural. The upstream end of the above-described relay line 26 is connected to the pump 25. In addition, the downstream end of the relay line 26 is opened in the service tank 22. Then, 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.

Like 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 in accordance with the atmospheric temperature. The service tank 22 maintains the LPG at a pressure above the saturated vapor pressure at the temperature in the service tank 22.

According to this embodiment, the service tank 22 is connected with an inert gas supply source not shown by the inert gas introduction line 54. The inert gas supply source is arranged in the engine room 11, for example. And, when inert gas (eg, 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 no inert gas is present in the service tank 22, the holding pressure of the service tank 22 is equal to the saturated vapor pressure of the LPG.

When LPG circulates between the engine 12 and the service tank 22 as mentioned later, the temperature of the service tank 22 may be higher than 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. Here, the service tank 22 is configured to withstand up to 2.0 MPa, for example.

The inert gas introduction line 54 is provided with a shutoff valve 55 and a pressure regulating valve 56 in order 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 control device 8. In FIG. 1, only some signal lines are shown for the sake of simplicity. The control device 8 is, for example, a computer having a CPU and a memory such as a ROM or a RAM, and a program stored in the ROM is executed by the CPU.

The control apparatus 8 is electrically connected with the pressure gauge 91 which detects the pressure (holding pressure) of the gaseous phase in the service tank 22. And the control apparatus 8 controls the shutoff valve 55 and the pressure regulating valve 56 so that the pressure detected by the pressure gauge 91 may not be less than the lower limit of an allowable range.

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

The pressure regulating valve 74 is controlled by the control device 8. The control device 8 controls the pressure regulating 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 here, the pressure line valve is also provided in the combustion line 73 to reduce the mixed gas supplied to the boiler 13 to 1.0 MPa or less.

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

The upstream end of the fuel supply line 31 is connected to the lower part of the service tank 22. On the other hand, the part (henceforth an extension in engine room) 31a which exists in the engine room 11 in the fuel supply line 31 is formed uphill toward the engine 12. As shown in FIG.

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

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

The downstream end of the fuel recovery line 41 is open in the service tank 22. On the other hand, the part (henceforth an extension in engine room) 41a which exists in the engine room 11 in the fuel recovery line 41 is formed in the downhill toward the engine 12. As shown in FIG.

The fuel recovery line 41 includes a first pressure regulating valve 42, a shutoff valve 43 (corresponding to a second shutoff valve of the present invention), a cooler 44, and a second pressure regulating valve 45 in order from an upstream side. (Corresponding to the pressure regulating valve of the present invention) is provided. These devices 42 to 45 are arranged outside of the engine room 11. More specifically, the first pressure regulating valve 42 and the shutoff valve 43 are disposed in the first appliance room 14, and the cooler 44 and the second pressure regulating valve 45 are the second appliance room 15. ) Is arranged in. The cooler 44 cools the LPG to a predetermined temperature (eg 40 ° C.).

The first pressure regulating valve 42, the shutoff valve 43 and the second pressure regulating valve 45 are controlled by the control device 8. Here, the control of the shutoff valve 43 is demonstrated in detail later. The control device 8 is electrically connected to the pressure gauge 92 for detecting the pressure of the LPG at the inlet of the engine 12 and the pressure gauge 93 for detecting the pressure of the LPG upstream of the second pressure regulating valve 45. It is connected. According to 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.

As for the first pressure regulating valve 42, the control device 8 controls the first pressure regulating valve 42 so that the pressure detected by the pressure gauge 92 becomes the required pressure of the engine 12. On the other hand, with respect to the second pressure regulating valve 45, the temperature of the LPG is slightly increased by passing the LPG through the engine 12 (for example, 55 ° C.), thus controlling the second pressure regulating valve 45. As a set value for, determine a set value at which the saturated steam pressure is at the assumed maximum temperature (for example, 2.0 MPa), so that the control device 8 causes the pressure detected by the pressure gauge 93 to be higher than the set value. The second pressure control valve 45 is controlled.

Alternatively, the control device 8 is electrically connected to a thermometer 81 for detecting the temperature of the LPG at the outlet of the engine 12, and the pressure detected by the pressure gauge 93 is the temperature at which the thermometer 81 is detected. The second pressure regulating valve 45 may be controlled to be higher than the saturated vapor pressure at.

Here, according to the present embodiment, the portion between the heater 33 of the fuel supply line 31 and the first shutoff valve 34 is connected to the shutoff valve of the fuel recovery line 41 by the bypass line 16. 43 is connected to the portion between the cooler 44. The bypass line 16 is provided with a flow control valve 17. The flow control valve 17 is controlled by the control device 8 so that the LPG passing through the engine 12 becomes a predetermined flow rate.

Moreover, the ship 1 has a structure for purging the extension part 31a of the engine compartment of the fuel supply line 31, and the extension part 41a of the engine compartment of the fuel recovery line 41 with inert gas, Comprising: The purge line 51, the 2nd purge line 61, and the purge tank 6 are provided.

The first purge line 51 connects the portion between the engine room 11 and the first pressure regulating valve 42 in the fuel recovery line 41 with an inert gas supply source, not shown above. That is, the inert gas is supplied to the fuel recovery line 41 between the engine room 11 and the first pressure regulating valve 42 via the first purge line 51. The shutoff valve 52 and the flow control apparatus are provided in the 1st purge line 51 sequentially from an upstream. The flow rate control device is the flow rate control valve 53 in the present embodiment, but may be an orifice or the like.

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

The second purge line 61 and the purge tank 6 extend in the engine room of the fuel recovery line 41 and extension 31a in the engine room of the fuel supply line 31 in the first appliance room 14. It is located below the part 41a.

In addition, the purge tank 6 is connected to the service tank 22 by the conveying line 63 and to the boiler 13 described above by the combustion line 71. The conveying line 63 is for returning the liquid LPG to the service tank 22, and the combustion line 71 is for guiding a mixed gas of vaporized PG and an inert gas to the boiler 13.

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

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

The above-mentioned shutoff valves 52, 62, 64, 72 and the flow control valve 53 are controlled by the control device 8. Hereinafter, the control of such a valve 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 the LPG between the service tank 22 and the engine 12 via the fuel supply line 31 and the fuel recovery line 41, the control device 8 is a shut-off valve of the first purge line 51. 52, the shutoff valve 62 of the second purge line 61, the shutoff valve 64 of the transfer line 63, and the shutoff valve 72 of the combustion line 71 are closed at the same time. The shutoff valve 34 of 31 and the shutoff valve 43 of the fuel recovery line 41 are opened. Accordingly, the LPG is circulated through the fuel supply line 31 and the fuel recovery line 41.

On the other hand, when performing the purge operation which purges the extension part 31a in the engine room of the fuel supply line 31, and the extension part 41a in the engine room of the fuel recovery line 41 with inert gas, the control apparatus 8 is carried out. Closes the first shutoff valve 34 of the fuel supply line 31, the shutoff valve 43 of the fuel recovery line 41, and the shutoff valve 52 of the first purge line 51; The shutoff valve 62 of the purge line 61 is opened. At this time, the shutoff valve 64 of the transfer line 63 and the shutoff valve 72 of the combustion line 71 are in a closed state.

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

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

Therefore, when the pressure detected by the pressure gauge 94 becomes a predetermined value (purge completion pressure: for example, 1.9 MPa) or more corresponding to the amount which can make an inert gas flow, the control apparatus 8 carries out a purge operation | work It is determined that it is completed. In addition, when the pressure necessary for conveying LPG from the purge tank 6 to the service tank 22 (LPG conveyance required pressure: for example, the gauge pressure 2.0 MPa) 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 pressurized. And when the pressure of the purge tank 6 became more than LPG conveyance required pressure, the control apparatus 8 will cut off the shutoff valve 52 of the 1st purge line 51, and the shutoff valve of the 2nd purge line 61 ( 62 is closed, and the shutoff valve 64 of the conveying line 63 is then opened. Accordingly, after completion of the purge operation, the LPG accumulated in the purge tank 6 can be returned to the service tank 22 through the transfer line 63 using the pressure of the inert gas.

When the transfer to the service tank 22 of the LPG is completed, the control device 8 closes the shutoff valve 64 of the transfer line 63 and simultaneously opens the shutoff valve 72 of the combustion line 71 to purge. The mixed gas of PG and inert gas remaining in the tank 6 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 have an extension part 31a in the engine room of the fuel supply line 31 and a fuel recovery line ( It is arrange | positioned below the extension part 41a in the engine room of 41. Therefore, when purging the extension part 41a in the engine room of the fuel recovery line 41 and the extension part 31a of the engine room of the fuel supply line 31 with an inert gas, LPG is supplied to the fuel supply line using gravity. It can be driven into the purge tank 6 from 31. Thus, the extension 41a in the engine room of the fuel recovery line 41 and the extension 31a in the engine room of the fuel supply line 31 can be easily purged with inert gas.

Further, according to 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 and the service tank 22 also have a fuel supply line 31 and The piping constituting the fuel recovery line 41 can be composed of ordinary steel, not low temperature steel such as nickel alloy. Therefore, the cost can be reduced.

Furthermore, according to the present embodiment, since the cooler 44 is provided in the fuel recovery line 41, the recovered LPG can be suppressed from flashing (rapid vaporization) in the service tank 22.

Further, according to the present embodiment, the LPG pressure upstream of the second pressure control valve 45 by the second pressure control valve 45 of the fuel recovery line 41 is higher than the saturated steam pressure at the assumed maximum temperature. Since it is adjusted to be high, it is possible to prevent the LPG from flashing in the fuel recovery line 41 (before the LPG is cooled in the cooler 44 in this embodiment).

(Variation)

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, if the backflow prevention valve is provided in the conveyance line 63, the shutoff valve 64 may not be closed when circulating the LPG between the service tank 22 and the engine 12.

Further, according to the above embodiment, although the fuel tank 2 was composed of the storage tank 21 and the service tank 22, the storage tank 21 is omitted so that the fuel tank 2 is replaced with the service tank 22 only. It may be comprised. However, if it is the same structure as the above embodiment, the fuel tank 2 can be divided into the storage tank 21 for LPG introduction and the service tank 22 for LPG circulation.

In addition, the extension part 31a in the engine room of the fuel supply line 31 does not necessarily need to be an uphill facing the engine 12, and may be arrange | positioned on a horizontal plane. Similarly, the extension part 41a in the engine room of the fuel recovery line 41 does not necessarily have to be downhill toward the engine 12, and may be disposed on the horizontal plane. However, with the same configuration as in the above embodiment, the extension in the engine room 41a of the fuel recovery line 41 and the extension in the engine room 31a of the fuel supply line 31 can be purged more easily with an inert gas. have.

In addition, inert gas does not necessarily need 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, if it is the same structure as the above embodiment, the holding pressure of the service tank 22 can be higher than the saturated steam pressure, and the necessary effective suction head NPSHr of the pump 32 for supplying the LPG to the engine 12 is secured. Becomes easy.

In addition, all the pressure control valves of the combustion line 71 are omitted, until the shutoff valve 72 of the combustion line 71 is omitted and the return of LPG from the purge tank 6 to the service tank 22 is completed. It may be closed.

In addition, the conveyance line 63 may be abbreviate | omitted and you may supply to the boiler 13 via the combustion line 71, vaporizing the whole quantity of LPG accumulated in the purge tank 6 after completion | finish of purge operation | work.

1: ship 11: engine room
12: propulsion engine 2: fuel tank
21: storage tank 22: service tank
24: Burner 25: Pump
31: fuel supply line 31a: extension in the engine compartment
34: shutoff valve (first shutoff valve) 41: fuel return line
41a: extension part in the engine room 43: shutoff valve (second shutoff valve)
51: first purge line 6: purge tank
61: second purge line 62: shutoff valve (third shutoff valve)
63: return line 64: shutoff valve (fourth shutoff valve)
8: control device

Claims (9)

A fuel tank for storing LPG,
A propulsion engine disposed in an engine room powered by LPG;
A fuel supply line for supplying LPG to the engine from the fuel tank and having a first shutoff valve installed outside the engine room;
A fuel recovery line for recovering LPG not used as the fuel tank from the engine and having a second shutoff valve installed outside the engine room;
A first purge line for supplying an inert gas to the fuel recovery line between the engine room and the second shutoff valve;
A purge tank connected to the fuel supply line between the engine room and the first shutoff valve by a second purge line provided with a third shutoff valve;
And the second purge line and the purge tank are disposed below the portion present in the engine room in the fuel supply line and the portion present in the engine room in the fuel recovery line.
The method of claim 1,
The portion present in the engine room in the fuel supply line is formed uphill toward the engine,
The portion of the fuel recovery line existing in the engine room is formed to the downhill toward the engine.
The method according to claim 1 or 2,
Further comprising a heater for heating the LPG supplied to the fuel tank to 0 ℃ or more,
The fuel tank maintains the LPG at a pressure equal to or higher than the saturated steam pressure at the temperature of the fuel tank.
The method according to any one of claims 1 to 3,
The fuel recovery line, the ship characterized in that the cooler for cooling the LPG to a predetermined temperature is installed.
The method according to any one of claims 1 to 4,
The fuel recovery line is provided with a pressure regulating valve, and the pressure regulating valve sets the pressure of the LPG upstream of the pressure regulating valve at a saturated steam pressure at the temperature of the LPG at the outlet of the engine or at an assumed maximum temperature. A vessel characterized in that it is adjusted to be higher than the saturated steam pressure of.
The method according to any one of claims 1 to 5,
The fuel tank includes a storage tank into which LPG is introduced, and a service tank supplied with LPG from the storage tank and connected to the engine by the fuel supply line and the fuel recovery line.
The method of claim 6,
Ship characterized in that the inert gas is introduced into the service tank.
The method according to any one of claims 1 to 7,
The purge tank is connected to the fuel tank through a transfer line provided with a fourth shutoff valve,
And a control device for controlling the first shutoff valve, the second shutoff valve, the third shutoff valve and the fourth shutoff valve.
The control device, when circulating the LPG between the fuel tank and the engine via the fuel supply line and the fuel recovery line, closes the third shutoff valve and simultaneously the first shutoff valve and the second shutoff valve. The first shut-off valve and the second when the 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 with inert gas. And closing the shutoff valve and the fourth shutoff valve and simultaneously opening the third shutoff valve and opening the fourth shutoff valve after the purge operation is completed.
The method according to any one of claims 1 to 8,
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 determines that the purge operation is completed when the pressure of the purge tank detected by the pressure gauge reaches a predetermined value or more.

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