WO2019050004A1

WO2019050004A1 - Ship and management method for lpg temperature/pressure

Info

Publication number: WO2019050004A1
Application number: PCT/JP2018/033258
Authority: WO
Inventors: 拓海野崎; 俊宏 ▲高▼木; 宏之武田; 尚子印藤; 和也萩原; 雄輝宍粟; 崇嗣安部; 直樹成島
Original assignee: 川崎重工業株式会社
Priority date: 2017-09-08
Filing date: 2018-09-07
Publication date: 2019-03-14
Also published as: KR102316444B1; JP6959804B2; SG11202001766UA; JP2019048507A; CN111065576B; KR20200047640A; CN111065576A

Abstract

The ship is provided with: a fuel tank, a propulsion engine, a fuel supply line, a pump, a fuel recovery line, a bypass line, a pressure gauge, and a control unit. The control unit causes the pump to operate when the pressure detected in the gas space of the fuel tank by the pressure gauge while LPG is not being used as fuel is a predetermined value or less and causes the LPG in the fuel tank to circulate via the engine and/or bypass line back to the fuel tank.

Description

Vessel and LPG Temperature / Pressure Management Method

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 light 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.

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 of engine while circulating LPG between the fuel tank and the engine Is considered.

By the way, when LPG is circulated between the fuel tank and the engine as described above, it is desirable to supply the engine with a little more fuel than the fuel consumption of the engine. In order to realize this, it is conceivable to adjust the rotational speed of the pump provided in the fuel supply line according to the fuel consumption of the engine. Moreover, in order to inject fuel appropriately in the engine, it is necessary to secure the fuel supply pressure to the engine at a certain value or more. For this reason, it is desirable to set a minimum number of revolutions for the pump.

For example, in order to keep LPG, which is the main component of propane gas, liquid at atmospheric pressure, it is necessary to keep the fuel tank at -42 ° C. or less. Therefore, it is conceivable to use the fuel tank as a pressure vessel and to change the temperature of the LPG in the fuel tank following the atmospheric temperature. That is, the high pressure in the fuel tank keeps the LPG in equilibrium. However, in this case, the pressure of the air layer in the fuel tank (the saturated vapor pressure in the case of only PG in which the components of the air layer are vaporized) largely changes depending on the temperature of the LPG in the fuel tank. When the temperature of the LPG in the fuel tank is low, the pressure width to which the pump should increase is large, and when the temperature of the LPG in the fuel tank is high, the pressure width to which the pump should increase is small.

Then, when the temperature of LPG in the fuel tank is low (when the pressure of the air layer is low and the pressure range to be boosted by the pump is large), when using LPG as fuel, the LPG supply pressure is used in the engine The pressure can not be increased to the required pressure, and the engine may not operate smoothly.

Then, an object of this invention is to provide the ship which can operate a propulsion engine smoothly at the time of LPG use start.

A ship according to one aspect of the present invention comprises a fuel tank storing LPG so that the temperature of LPG changes following the atmospheric temperature, a propulsion engine using LPG as fuel, and LPG to the engine from the fuel tank A fuel supply line for supplying fuel, a pump provided in the fuel supply line, a fuel recovery line for recovering unused LPG from the engine to the fuel tank, and pressure of an air layer in the fuel tank A pressure gauge and a control device for controlling the number of revolutions of the pump, wherein the control device controls the pressure detected by the pressure gauge during a period when the LPG is not being used as a fuel or less. The pump is operated to circulate LPG in the fuel tank to the fuel tank via the engine.

A ship according to another aspect of the present invention comprises a fuel tank for storing LPG so that the temperature of LPG changes following the atmospheric temperature, a propulsion engine using LPG as fuel, and LPG to the engine from the fuel tank A fuel supply line for supplying fuel, a pump provided in the fuel supply line, a fuel recovery line for recovering unused LPG from the engine to the fuel tank, and a branch from the fuel supply line downstream of the pump The fuel recovery line or a bypass line connected to the fuel tank, a pressure gauge for detecting the pressure of the air layer in the fuel tank, and a control device for controlling the number of revolutions of the pump; Operates the pump when the pressure detected by the pressure gauge is below a predetermined value while LPG is not being used as fuel, The LPG in serial fuel tank through the engine and / or the bypass line is circulated to the fuel tank.

According to an LPG temperature / pressure management method according to one aspect of the present invention, a fuel tank storing LPG such that the temperature of LPG changes following the atmospheric temperature, a propulsion engine using LPG as fuel, and the fuel tank Applied to a ship including a fuel supply line for supplying LPG from the engine to the engine, a pump provided in the fuel supply line, and a fuel recovery line for recovering unused LPG from the engine to the fuel tank LPG temperature / pressure management method, wherein LPG is not used as fuel under the condition that the pressure of the air layer in the fuel tank falls below a predetermined value, the temperature of LPG in the fuel tank falls below the predetermined value The pump is operated when the above condition and / or the condition that the pump operation command member is operated by a crew member is satisfied, and the fuel tank is The LPG through the engine is circulated into the fuel tank.

According to the above configuration, if the pressure of the air layer is low while LPG is not being used as fuel, the pump operates to circulate LPG. The temperature of the LPG rises with heat input from the pump as it passes through the pump. In addition, it can rise by the heat input from an engine also at the time of passage of an engine. Thus, the temperature of LPG in the fuel tank can be raised and the pressure of the air layer can also be raised by returning the temperature of the LPG heated in the circulation process back to the fuel tank. Therefore, at the start of use of LPG, the pump can boost the supply pressure of LPG to the pressure required by the engine, and the engine can be operated smoothly.

ADVANTAGE OF THE INVENTION According to this invention, the ship which can operate a propulsion engine smoothly can be provided at the time of LPG use start.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the ship which concerns on 1st Embodiment. It is a schematic block diagram of the ship concerning a modification. It is a schematic block diagram of the ship concerning a 2nd embodiment.

Hereinafter, embodiments will be described with reference to the drawings. The same or corresponding elements will be denoted by the same reference symbols throughout the drawings, without redundant description.

First Embodiment
FIG. 1 shows a ship according to the first embodiment. The ship 1 includes a fuel tank 2 storing LPG so that the temperature of the LPG changes following the atmospheric temperature, and a propulsion engine 11 using the LPG as fuel. The main component of LPG may be propane (propane gas) or butane (butane gas).

In the present embodiment, the fuel tank 2 is configured of a storage tank 21 having a relatively large volume and a service tank 22 having a relatively small volume. The storage tank 21 and the service tank 22 are both pressure vessels whose pressure resistance is higher than atmospheric pressure. 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.

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 is connected to the pump 25. The downstream end of the relay line 26 opens in the service tank 22. 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.

In the present embodiment, the storage tank 21 is not provided with means (for example, a heat insulating material) for maintaining the LPG at a low temperature, and the temperature of the LPG in the storage tank 21 changes following the atmospheric temperature. On the other hand, LPG introduced from the LPG source is often about -42 ° C. when LPG is propane gas. Therefore, the fuel introduction line 23 is provided with a heater 24 for heating the LPG to, for example, −5 ° C. or higher. 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 -5 ° C or higher, the heater 24 is unnecessary. is there.

In the case of only PG in which the component of the air layer in the storage tank 21 is vaporized, the pressure of the air layer in the storage tank 21 is the saturated vapor pressure of LPG. For example, when the temperature in the storage tank 21 is 25 ° C., the pressure (saturated vapor pressure) of the air layer in the storage tank 21 is about 0.9 MPa in gauge pressure. Hereinafter, all indications of pressure are gauge pressures. In addition, since the saturated vapor pressure of LPG is about 1.7 MPa at 50 ° C., the storage tank 21 is configured to withstand, for example, 1.8 MPa. For reference, the saturated vapor pressure of LPG is about 0.4 MPa at 0 ° C.

Similar to the storage tank 21, the service tank 22 is not provided with means for maintaining the LPG at a low temperature, and the temperature of the LPG in the service tank 22 changes following the atmospheric temperature. When the component of the air layer in the service tank 22 is only vaporized PG, the pressure of the air layer in the service tank 22 is the saturated vapor pressure of LPG.

During circulation of LPG between the engine 11 and the service tank 22 as described later, the temperature of the LPG in the service tank 22 may be higher than the ambient temperature. For example, when the temperature of LPG in the service tank 22 is 60 ° C., the pressure (saturated vapor pressure) of the gas layer in the service tank 22 is about 2.1 MPa. The service tank 22 is configured to withstand, for example, 2.2 MPa.

The service tank 22 is connected to the propulsion engine 11 by a fuel supply line 31 and a fuel recovery line 41. LPG is supplied from the service tank 22 to the engine 11 through the fuel supply line 31, and unused LPG is recovered from the engine 11 to the service tank 22 through the fuel recovery line 41. In other words, LPG circulates between the service tank 22 and the engine 11 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. The downstream end of the fuel recovery line 41 opens in the service tank 22.

The engine 11 is, for example, a diesel cycle or Otto cycle reciprocating engine. Although not shown, the engine 11 includes a main flow path connecting the downstream end of the fuel supply line 31 and the upstream end of the fuel recovery line 41, and a plurality of fuel injection valves connected in parallel to the main flow path. .

The fuel supply line 31 is provided with a pump 32, a heater 33 and a shutoff valve 34 in this order from the upstream side. The heater 33 heats the LPG to the required temperature (for example, 45 ° C.) of the engine 11.

The relay line 26 is provided with a heater 27 for heating the LPG supplied from the storage tank 21 to the service tank 22. While the engine 11 is in operation, the LPG is supplied from the storage tank 21 to the service tank 22 in an amount corresponding to the fuel consumption amount Qe of the engine 11. The heater 27 is used when it is difficult to heat the LPG to the required temperature of the engine 11 by the heater 33 alone. The heater 27 may be omitted.

In the fuel recovery line 41, a first pressure control valve 42, a shutoff valve 43, a cooler 44 and a second pressure control valve 45 are provided in this order from the upstream side. The cooler 44 cools the LPG to a predetermined temperature (for example, 40 ° C.). The cooler 44 may be omitted.

In the present embodiment, the fuel supply line 31 and the fuel recovery line 41 are connected by the first bypass line 51. The first bypass line 51 branches from the fuel supply line 31 between the heater 33 and the shutoff valve 34, and is connected to the fuel recovery line 41 between the shutoff valve 43 and the cooler 44. A flow control valve 52 is provided in the first bypass line 51.

Furthermore, in the present embodiment, the second bypass line 53 is also adopted. The second bypass line 53 branches from the fuel supply line 31 between the pump 32 and the heater 33 and is connected to the service tank 22. The second bypass line 53 is provided with a flow control valve 54. However, either one of the first bypass line 51 and the second bypass line 53 may be omitted.

The pump 32, the

shutoff valves

34 and 43, the

pressure control valves

42 and 45, and the

flow control valves

52 and 54 described above are controlled by the controller 6. However, in FIG. 1, only some signal lines are drawn for simplification of the drawing. The control device 6 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 6 may be a single device or may be divided into a plurality of devices (for example, an engine control device and a fuel supply control device).

The controller 6 is electrically connected to the first to third pressure gauges 71 to 73 and the flow meter 81. The first pressure gauge 71 and the flow meter 81 are used to control the pump 32 and the

flow control valves

52, 54, the second pressure gauge 72 is used to control the first pressure regulating valve 42, and the third pressure gauge 73 is 2 used for control of the pressure control valve 45.

Here, the engine 11 may be an engine using only LPG as a fuel, or may be a binary fuel engine using LPG and a fuel oil such as heavy oil or light oil as fuel.

In the case of an engine using only LPG as fuel, the timing to start using LPG as fuel corresponds to the timing to start operation of the engine 11. The period in which the use of the LPG is stopped corresponds to the period in which the engine 11 is stopped.

In the case of a dual fuel engine, the timing at which the operation of the engine 11 starts and the timing at which the operation of the engine 11 starts and the fuel used by the engine 11 is switched to the LPG And timing of adding LPG to the fuel used in The period in which the use of LPG is stopped includes a period in which the engine 11 is stopped and a period in which the engine 11 is operated using only fuel oil as fuel.

The control device 6 closes the

shutoff valves

34 and 43 while the

shutoff valves

34 and 43 are not supplying the LPG to the engine 11. While LPG is being supplied to the engine 11, the controller 6 opens the

shutoff valves

34 and 43. While the engine 11 is stopped, the flow passage between the shutoff valves 34 and 43 (the downstream portion of the fuel supply line 31, the main flow passage of the engine 11 and the upstream portion of the fuel recovery line 41) is purged with an inert gas.

When LPG is used as fuel in the engine 11, pressure control, flow control and temperature control of the LPG are performed as described below.

The first pressure gauge 71 is provided in the service tank 22 and detects the pressure of the air layer in the service tank 22. A flowmeter 81 is provided in the fuel supply line 31 downstream of a branch point with the first bypass line 51, and detects a supply flow rate Qi of the LPG flowing into the engine 11 through the fuel supply line 31. The controller 6 keeps the flow control valve 52 fully closed as long as the number of revolutions of the pump 32 does not reach the minimum number of revolutions. Then, the control device 6 controls the pump 32 such that the supply flow rate Qi detected by the flow meter 81 becomes a predetermined value V corresponding to the fuel consumption amount Qe of the engine 11. In the present embodiment, the predetermined value V is a value obtained by multiplying the fuel consumption amount Qe of the engine 11 by the coefficient C (V = Qe × C). For example, the coefficient C is usually 1.1 to 1.50. The coefficient C may be a fixed value set within this numerical range, or may be variably set within this numerical range.

For example, the control device 6 may determine the fuel consumption amount Qe of the engine 11 based on the operation amount of the telegraph lever operated by the operator. Alternatively, when the control device 6 is divided into an engine control device that controls the engine 11 and a fuel supply control device that controls the pump 32 and various valves, the fuel supply control device is calculated by the engine control device. The fuel consumption Qe of the engine 11 may be determined based on the value related to the fuel consumption.

As a result of control based on the supply flow rate Qi detected by the flow meter 81, when the number of rotations of the pump 32 becomes the minimum number of rotations, the controller 6 controls the supply flow rate Qi detected by the flow meter 81 to the predetermined value V described above. One of the

flow control valves

52 and 54 is controlled so that Specifically, the controller 6 increases the opening degree of one of the

flow control valves

52 and 54 as the fuel consumption amount Qe of the engine 11 decreases.

The second pressure gauge 72 is provided on the fuel supply line 31 downstream of the heater 33 and detects the pressure of the LPG supplied to the engine 11. In the present embodiment, the second pressure gauge 72 is located downstream of the shutoff valve 34, but may be located upstream of the shutoff valve 34. The control device 6 controls the first pressure control valve 42 so that the pressure detected by the second pressure gauge 72 becomes the required pressure of the engine 11 (for example, 5.0 to 6.0 MPa).

The third pressure gauge 73 is provided on the fuel recovery line 41 between the first pressure regulating valve 42 and the second pressure regulating valve 45, and detects the pressure of the LPG after the pressure is reduced by the first pressure regulating valve 42. Do. In the present embodiment, the third pressure gauge 73 is located upstream of the cooler 44, but may be located downstream of the cooler 44.

The temperature of the LPG rises a little as the LPG passes through the engine 11 (for example, 55 ° C.). Therefore, in order to prevent the LPG decompressed by the first pressure regulating valve 42 from being vaporized, the controller 6 determines that the pressure detected by the third pressure gauge 73 is higher than the saturated vapor pressure at the maximum temperature assumed. The second pressure control valve 45 is controlled to have a high set value (for example, 2.0 MPa).

Temperature control and hence pressure control of the LPG are also performed when the use of the LPG is stopped. In particular, temperature control of the LPG in the fuel tank 2 and control of the pressure of the air layer in the fuel tank 2 are performed.

Specifically, when the LPG is not used as fuel, the pressure of the air layer in the service tank 22 detected by the first pressure gauge 71 is equal to or less than a predetermined value during a period when the LPG is not used as fuel, or When the pump command member 61 is operated by the operator, the pump 32 is operated. At this time, any one of the

shutoff valves

34 and 43 and / or the

flow control valves

52 and 54 is opened. When the

shutoff valves

34 and 43 are opened, the LPG in the service tank 22 circulates to the service tank 22 via the fuel supply line 31 and the engine 11 (particularly, its main flow path). When the flow control valve 52 is opened, the LPG in the service tank 22 circulates to the service tank 22 via the fuel supply line 31 and the first bypass line 51. When the flow control valve 54 is opened, the LPG in the service tank 22 circulates to the service tank 22 via the fuel supply line 31 and the second bypass line 53. When any one of the

shutoff valves

34 and 43 and the

flow control valves

52 and 54 is open, the LPG in the service tank 22 is the engine 11 and the fuel recovery line 41, and / or the first bypass line 51 or It circulates to the service tank 22 via the second bypass line 53.

As described above, when the temperature of LPG in the service tank 22 is 0 ° C., the pressure of the air layer of the service tank 22 (saturated vapor pressure of LPG) is about 0.4 MPa, while LPG is used as fuel The required pressure of the engine 11 in use is 5.0 to 6.0 MPa. If the pressure of the air layer in the service tank 22 is lower than a predetermined value, even if it is desired to operate the engine 11 using LPG as fuel, the pump 32 can not boost the supply pressure of LPG to the required pressure. I can not drive. The LPG can not be used to drive the engine 11 until the required pressure can be reached (until the pressure in the air layer exceeds the predetermined value). It will be delayed by a minute.

As described above, when the control device 6 circulates LPG through the engine 11 and / or the first bypass line 51 or the second bypass line 53 while the LPG is not used as fuel, the temperature of the LPG Increases with the heat input from the pump 32 at least. In the case of a dual fuel engine, if the engine 11 is operating using fuel oil, the LPG passes through the engine 11 and circulates, so that the heat is also received from the engine 11 and it becomes easy to raise the temperature of the LPG. Further, in the present embodiment, since the heater 33 is disposed on the fuel supply line 31 between the branch point of the pump 32 and the first bypass line 51, LPG circulation via the first bypass line 51 is achieved. Even at the same time, the temperature of the LPG can be raised by the heater 33. The cooler 44 is a temperature controller that controls the temperature of the LPG to a temperature lower than that of the heater 33. Therefore, when LPG is circulated due to low pressure, the temperature of the LPG is lower than the adjustment temperature of the cooler 44. Therefore, the "cooler 44" can function as a heater.

Due to the circulation of the LPG, the temperature of the LPG in the service tank 22 rises, and the pressure of the air layer in the service tank 22 (the saturated vapor pressure of LPG) also rises accordingly. If the pressure in the air layer exceeds a predetermined value, the pump 32 is stopped to stop the circulation of the LPG. Note that the threshold value of the circulation stop determination may be set to a value (high pressure value) larger than the threshold value of the circulation start determination in order to prevent the operation and stop of the pump 32 from being repeated frequently.

The rotational speed of the pump 32 is not particularly limited, but may be constant at the minimum rotational speed, or may be variable according to the pressure of the air layer to be detected. By raising the rotational speed of the pump 32 when the pressure in the air layer is low, the temperature can be raised early.

As described above, when the use of LPG is stopped, the pressure of the air layer in the service tank 22 is maintained at a predetermined value or more, so when the LPG starts to be used as fuel, the supply pressure of the LPG by the pump 32 Can be boosted to the pressure required by the engine 11, and the engine operation using the LPG can be smoothly and rapidly started.

Second Embodiment
FIG. 2: is a schematic block diagram of the ship 101 which concerns on 2nd Embodiment. As shown in FIG. 2, the

bypass lines

51 and 53 and the

flow control valves

52 and 54 may be omitted. In this case, the control device 6 operates the pump 32 when the pressure of the air layer in the service tank 22 detected by the first pressure gauge 71 is less than or equal to a predetermined value when the use of the LPG is stopped. , LPG in the service tank 22 is circulated to the service tank 22 via the engine 11. Also in this embodiment, as in the first embodiment, when LPG is started to be used as fuel, the pump 32 can boost the supply pressure of LPG to the pressure required by the engine 11, and the engine using LPG Driving can be started smoothly and quickly.

(Modification)
FIG. 3 is a schematic configuration view of a ship 201 according to a modification. As shown in FIG. 3, a flow meter 81 may be provided on the fuel recovery line 41 upstream of the shutoff valve 43 to detect an outflow flow rate Qo of the LPG from the engine 11. That is, the control device 6 may control the pump 32 and the flow control valve 52 such that the outflow flow rate Qo detected by the flow meter 81 becomes a predetermined value V 'corresponding to the fuel consumption amount Qe of the engine 11. . In this case, the predetermined value V ′ is, for example, a value obtained by multiplying the fuel consumption amount Qe of the engine 11 by a coefficient C of usually 0.1 to 0.50. Also in this case, the coefficient C may be a fixed value set within the numerical value range, or may be variably set within the numerical value range.

The predetermined values V and V 'do not necessarily have to be constant, and the control device 6 may increase the predetermined values V and V' when the number of rotations of the pump 32 reaches the minimum number of rotations. For example, in the configuration shown in FIG. 1, the predetermined value V may be increased to a flow rate in the range of 1.1 × Qe to 11.0 × Qe. Alternatively, in the configuration shown in FIG. 3, the predetermined value V ′ may be increased to a flow rate in the range of 0.1 × Qe to 10.0 × Qe.

The predetermined values V and V 'are constant when the rotational speed of the pump 32 reaches the minimum rotational speed, and the flow control valve 54 provided in the second bypass line 53 is opened. The surplus amount obtained by subtracting the predetermined values V and V ′ from the discharge flow rate Q is returned to the service tank 22 through the second bypass line 53. Since the surplus is heated by the pump 32, the temperature of the LPG in the service tank 22 rises. On the other hand, if the predetermined values V and V 'are increased when the rotational speed of the pump 32 reaches the minimum rotational speed, the LPG returned to the service tank 22 through the second bypass line 53 can be reduced. . On the other hand, although the LPG passing through the engine 11 is also increased by the increase of the predetermined values V and V ', the increased amount is cooled by the cooler 44 provided in the fuel recovery line 41. Therefore, the rise of the temperature of the LPG in the service tank 22 can be suppressed.

In the above embodiment, the fuel tank 2 is configured of the storage tank 21 and the service tank 22. However, the storage tank 21 may be omitted, and the fuel tank 2 may be configured of only the service tank 22. That is, LPG may be directly introduced into the service tank 22 from the LPG supply source. 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.

Since the pressure (saturated vapor pressure) of the air layer in the service tank 22 depends on the temperature in the service tank 22, the temperature in the service tank 22 (even in the air layer temperature) does not depend on the first pressure gauge 71. A thermometer may be provided to detect the temperature of the pump 32 and the necessity of operation of the pump 32 may be determined according to the temperature detected by the thermometer.

1, 101, 201 Vessel 11 Propulsion engine 2 Fuel tank 6 Control device 31 Fuel supply line 32 Pump 41 Fuel recovery line 51, 251 Bypass line 61 Pump operation command member 71 First pressure gauge

Claims

A fuel tank for storing LPG so that the temperature of the LPG changes following the ambient temperature;
A propulsion engine powered by LPG,
A fuel supply line for supplying LPG from the fuel tank to the engine;
A pump provided in the fuel supply line;
A fuel recovery line for recovering unused LPG from the engine to the fuel tank;
A pressure gauge for detecting the pressure of the air layer in the fuel tank;
A controller for controlling the number of revolutions of the pump;
When the pressure detected by the pressure gauge is equal to or less than a predetermined value during a period in which LPG is not used as fuel, the control device operates the pump and LPG in the fuel tank through the engine. A vessel that circulates to the fuel tank.
A fuel tank for storing LPG so that the temperature of the LPG changes following the ambient temperature;
A propulsion engine powered by LPG,
A fuel supply line for supplying LPG from the fuel tank to the engine;
A pump provided in the fuel supply line;
A fuel recovery line for recovering unused LPG from the engine to the fuel tank;
A bypass line branched from the fuel supply line downstream of the pump and connected to the fuel recovery line or the fuel tank;
A pressure gauge for detecting the pressure of the air layer in the fuel tank;
A controller for controlling the number of revolutions of the pump;
When the pressure detected by the pressure gauge is equal to or less than a predetermined value while LPG is not being used as fuel, the control device operates the pump to set the LPG in the fuel tank to the engine and / or A vessel that circulates to the fuel tank via the bypass line.
A fuel tank for storing LPG so that the temperature of the LPG changes following the ambient temperature;
A propulsion engine powered by LPG,
A fuel supply line for supplying LPG from the fuel tank to the engine;
A pump provided in the fuel supply line;
And a fuel recovery line for recovering unused LPG from the engine to the fuel tank.
The condition that the pressure of the air layer in the fuel tank falls below a predetermined value, the condition that the temperature of LPG in the fuel tank falls below a predetermined value, and / or the crew during a period when LPG is not used as fuel The LPG temperature / pressure management method, wherein the pump is operated to circulate LPG in the fuel tank to the fuel tank via the engine when the condition that the pump operation command member is operated is satisfied.