KR20200047640A - Ship and LPG temperature / pressure management method - Google Patents

Abstract

The ship is equipped 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 device. The control device operates the pump when the pressure of the base layer in the fuel tank detected by the pressure gauge is equal to or less than a predetermined value during a period when LPG is not used as fuel, and the LPG in the fuel tank is fueled through the engine and / or bypass line. Circulate to the tank.

Description

Ship and LPG temperature / pressure management method

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

In a conventional ship, in general, the fuel for the propulsion engine is fuel oil such as heavy oil or light oil or LNG (Liquefied Natural Gas). Recently, it has been proposed to use LPG (Liquefied Petroleum Gas) as a fuel for a propulsion engine. For example, the patent document discloses a ship that supplies LPG from a fuel tank to a propulsion engine while being liquid.

Korean Patent Publication No. 2012-0113398

When LPG is used as fuel, it is considered that the fuel tank and the propulsion engine are connected by a fuel supply line and a fuel recovery line, and only the necessary amount is used in the engine while circulating LPG between the fuel tank and the engine.

However, when LPG is circulated between the fuel tank and the engine as described above, it is preferable to supply the engine with slightly more fuel than the fuel consumption of the engine. To realize this, it is conceivable to adjust the number of revolutions of the pump installed on the fuel supply line in correspondence with the fuel consumption of the engine. In addition, in order to properly inject fuel in the engine, it is necessary to secure the fuel supply pressure to the engine above a certain value. Therefore, it is desirable to set the minimum rotational speed of the pump.

For example, in order to maintain LPG, which is a main component of propane gas, as a liquid at atmospheric pressure, it is necessary to keep the fuel tank at -42 ° C or lower. Therefore, it is considered to change the temperature of the LPG in the fuel tank by following the atmospheric temperature, using the fuel tank as a pressure vessel. That is, LPG is maintained in a balanced state by high pressure in the fuel tank. However, in such a case, the pressure of the base layer in the fuel tank (saturated vapor pressure when the component of the base layer is only vaporized PG) varies greatly 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 at which the pump pressure rises is large, and when the temperature of the LPG in the fuel tank is high, the pressure width at which the pump pressure rises is small.

Then, when the temperature of the LPG in the fuel tank is low (the pressure of the base layer is low and the pressure width at which the pump pressure rises is large), when the LPG is used as fuel, the supply pressure of the LPG to the pressure required by the engine There is a possibility that it cannot be boosted and the engine cannot be operated smoothly.

Accordingly, an object of the present invention is to provide a ship capable of smoothly driving a propulsion engine at the start of LPG use.

The ship according to an example of the present invention, a fuel tank for storing LPG so that the temperature of the LPG changes by following the atmospheric temperature, a propulsion engine using LPG as fuel, and supplying LPG to the engine from the fuel tank A fuel supply line, a pump installed in the fuel supply line, a fuel recovery line for recovering LPG that is not used as the fuel tank from the engine, a pressure gauge for detecting the pressure in the base layer in the fuel tank, and rotation of the pump A control device is provided for controlling the number, and when the pressure detected by the pressure gauge is equal to or less than a predetermined value during a period when LPG is not used as fuel, the pump is operated to recall LPG in the fuel tank. Circulate through the engine to the fuel tank.

The ship according to another example of the present invention, a fuel tank for storing LPG so that the temperature of the LPG changes by following the atmospheric temperature, a propulsion engine using LPG as fuel, and supplying LPG to the engine from the fuel tank A fuel supply line, a pump installed in the fuel supply line, a fuel recovery line for recovering LPG that is not used as the fuel tank from the engine, and a branch from the fuel supply line at the downstream side of the pump to return the fuel recovery line Or a bypass line connected to the fuel tank, a pressure gauge for detecting the pressure of the base layer in the fuel tank, and a control device for controlling the rotational speed of the pump, the control device, LPG is not used as fuel When the pressure detected by the pressure gauge is less than or equal to a predetermined value during the non-period, the pump is operated to extract LPG in the fuel tank. Circulate through the engine and / or the bypass line to the fuel tank.

LPG temperature / pressure management method according to an embodiment of the present invention, the fuel tank for storing LPG so that the temperature of the LPG changes in accordance with the atmospheric temperature, a propulsion engine using LPG as fuel, and the engine from the fuel tank As a LPG temperature / pressure management method applied to a ship having a fuel supply line for supplying LPG, a pump installed in the fuel supply line, and a fuel recovery line for recovering LPG that is not used as the fuel tank from the engine In the period when LPG is not used as fuel, the condition that the pressure of the base layer in the fuel tank is lower than the predetermined value, the condition that the temperature of the LPG in the fuel tank is lower than the predetermined value, and / or the absence of the pump operation command by the crew When the condition of being operated is satisfied, the pump is operated to circulate LPG in the fuel tank through the engine to the fuel tank.

According to the above configuration, when the pressure of the base layer is low in a period when LPG is not used as fuel, the pump is operated to circulate the LPG. The temperature of LPG rises due to heat input from the pump when the pump passes. Here, even when the engine passes, it rises due to heat input from the engine. By returning the heated LPG to the fuel tank in this circulation process, the temperature of the LPG in the fuel tank can be increased, and the pressure of the base layer can be increased. Therefore, when the use of LPG is started, the supply pressure of LPG from the pump can be increased to the pressure required by the engine, and the operation of the engine can be smoothly performed.

According to the present invention, it is possible to provide a ship capable of smoothly driving a propulsion engine at the start of LPG use.

1 is a schematic configuration diagram of a ship according to a first embodiment.
2 is a schematic configuration diagram of a ship according to a modification.
3 is a schematic configuration diagram of a ship according to a second embodiment.

Hereinafter, embodiments will be described with reference to the drawings. Throughout the drawings, the same reference numerals are assigned to the same or corresponding elements, and duplicate detailed descriptions are omitted.

(First Example)

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

According to this embodiment, the fuel tank 2 is composed of a relatively large volume storage tank 21 and a relatively small volume service tank 22. The storage tank 21 and the service tank 22 together are pressure vessels whose internal pressure is higher than atmospheric pressure. The storage tank 21 and the service tank 22 are connected to each other by a relay line 26.

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

A pump 25 is installed inside the storage tank 21. The number of pumps 25 may be one or plural. The upstream end of the relay line 26 is connected to the pump 25. The downstream end of the relay line 26 is opening in the service tank 22. By the pump 25, LPG is supplied from the storage tank 21 to the service tank 22 via the relay line 26. However, the pump 25 may be provided in the middle of the relay line 26 from the outside of the storage tank 21.

According to this embodiment, the storage tank 21 is not provided with a means (for example, a heat insulating material) for maintaining LPG at a low temperature, and the temperature of the LPG in the storage tank 21 changes according to the atmospheric temperature. The LPG introduced from the LPG source is often about -42 ° C when the LPG is propane gas. Therefore, the fuel introduction line 23 is provided with a heater 24 for heating the LPG to a temperature ranging from -5 ° C to atmospheric temperature, for example. However, since a heater is installed in an LPG supply facility on the ground or an LPG fuel supply line that is an LPG supply source, the heater 24 is unnecessary when the temperature of the LPG delivered to the ship 1 is -5 ° C or higher.

When the component of the base layer in the storage tank 21 is only the vaporized PG, the pressure of the base 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 base layer in the storage tank 21 is about 0.9 MPa as a gauge pressure. Hereinafter, all the indications of pressure are gauge pressures. Here, 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.

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

When LPG is circulated 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 atmospheric temperature. For example, when the temperature of LPG in the service tank 22 is 60 ° C, the pressure (saturated vapor pressure) of the base layer in the service tank 22 is about 2.1 MPa. Here, 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 via 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 is circulated through the fuel supply line 31 and the fuel recovery line 41 between the service tank 22 and the engine 11.

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 is opening in the service tank 22.

The engine 11 is, for example, a diesel cycle or an auto 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 to the main flow path in parallel with each other. do.

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

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

The fuel recovery line 41 is provided with a first pressure regulating valve 42, a shut-off valve 43, a cooler 44 and a second pressure regulating valve 45 in order from the upstream side. The cooler 44 cools the LPG to a predetermined temperature (eg, 40 ° C). Here, the cooler 44 may be omitted.

According to this 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 the fuel recovery line 41 between the shutoff valve 43 and the cooler 44. ). A flow control valve 52 is installed in the first bypass line 51.

Further, according to this embodiment, the second bypass line 53 is also employed. 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. A flow control valve 54 is installed in the second bypass line 53. However, either one of the first bypass line 51 and the second bypass line 53 may be omitted.

The above-described pump 32, shut-off valves 34, 43, pressure regulating valves 42, 45 and flow control valves 52, 54 are controlled by the control device 6. However, in FIG. 1, only some signal lines are depicted for simplification of the drawing. The control device 6 is, for example, a computer having a memory and a CPU such as ROM or RAM, 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 control device 6 is electrically connected to the first to third pressure gauges 71 to 73 and the flowmeter 81. The first pressure gauge 71 and the flow meter 81 are used for the control of the pump 32 and the flow control valves 52 and 54, and the second pressure gauge 72 is used for the control of the first pressure regulating valve 42, , The third pressure gauge 73 is used to control the second pressure regulating valve 45.

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

In the case of an engine using only LPG as fuel, the timing of starting to use LPG as fuel corresponds to the timing of starting the operation of the engine 11. The period of stopping the use of LPG corresponds to the period of stopping the engine 11.

In the case of a binary fuel engine, when starting to use LPG as fuel, the timing of starting the operation of the engine 11 and the engine 11 are running, but the fuel used in the engine 11 is converted into LPG or the engine 11 The timing of adding LPG to the fuel used in) is included. 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.

Regarding the shut-off valves 34 and 43, the control device 6 closes the shut-off valves 34 and 43 in a period in which supply of LPG to the engine 11 is stopped. During the period when LPG is supplied to the engine 11, the control device 6 opens the shut-off valves 34 and 43. During the stoppage of the engine 11, the flow paths between the shut-off valves 34 and 43 (the downstream side portion of the fuel supply line 31, the main flow path of the engine 11, and the upstream side portion of the fuel recovery line 41) are It is purged with an inert gas.

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

The first pressure gauge 71 is installed in the service tank 22 and detects the pressure of the base layer in the service tank 22. The flow meter 81 is installed in the fuel supply line 31 at the downstream side of the branching point with the first bypass line 51, and the supply flow rate of LPG flowing into the engine 11 through the fuel supply line 31 (Qi) is detected. The control device 6 keeps the flow rate control valve 52 all closed unless the rotational speed of the pump 32 is the lowest rotational speed. 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. do. According to this embodiment, the predetermined value V is a value obtained by multiplying the fuel consumption amount Qe of the engine 11 by a coefficient C (V = Qe × C). For example, the coefficient C is generally 1.1 to 1.50. The coefficient C may be a fixed value set within such a numerical range, or may be variably set within such a 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. You may determine the fuel consumption amount Qe of the engine 11 based on the value regarding the consumed fuel consumption amount.

As a result of the control based on the supply flow rate Qi detected by the flow meter 81, when the rotational speed of the pump 32 reaches the lowest rotational speed, the control device 6 supplies the supply flow rate Qi detected by the flowmeter 81. One of the flow control valves 52 and 54 is controlled to have the above-described predetermined value V. Specifically, the control device 6 increases the opening degree of either 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 installed on the fuel supply line 31 on the downstream side of the heater 33, and detects the pressure of LPG supplied to the engine 11. According to this embodiment, the second pressure gauge 72 is located on the downstream side of the shut-off valve 34, but may be located on the upstream side of the shut-off valve 34. The control device 6 controls the first pressure regulating valve 42 so that the pressure detected by the second pressure gauge 72 becomes the required pressure of the engine 11 (eg, 5.0 to 6.0 MPa).

The third pressure gauge 73 is installed in the fuel recovery line 41 between the first pressure regulating valve 42 and the second pressure regulating valve 45, after being depressurized in the first pressure regulating valve 42. The pressure of LPG is detected. According to this embodiment, the third pressure gauge 73 is located on the upstream side of the cooler 44, but may be located on the downstream side of the cooler 44.

The temperature of LPG is slightly increased by passing LPG through the engine 11 (for example, 55 ° C). Accordingly, in order to prevent the LPG decompressed at the first pressure regulating valve 42 from vaporizing, the control device 6 is configured such that the pressure detected by the third pressure gauge 73 is higher than the saturated vapor pressure at the expected maximum temperature. The second pressure regulating valve 45 is controlled to be a set value (eg, 2.0 MPa).

Even when the use of LPG is stopped, temperature control of LPG and pressure control are performed. In particular, temperature management of the LPG in the fuel tank 2 and pressure control of the base layer in the fuel tank 2 are performed.

Specifically, the control device 6 pumps when the pressure of the base layer in the service tank 22 detected by the first pressure gauge 71 is less than or equal to a predetermined value during a period when LPG is not used as fuel, or by a crew When the command member 61 is operated, the pump 32 is operated. At this time, one of the shut-off valves 34 and 43 and / or the flow control valves 52 and 54 is opened. When the shutoff valves 34 and 43 are opened, LPG in the service tank 22 circulates through the fuel supply line 31 and the engine 11 (especially its main flow path) to the service tank 22. When the flow control valve 52 is opened, LPG in the service tank 22 circulates through the fuel supply line 31 and the first bypass line 51 to the service tank 22. When the flow control valve 54 is opened, LPG in the service tank 22 circulates through the fuel supply line 31 and the second bypass line 53 to the service tank 22. When either of the shut-off valves 34, 43 and the flow control valves 52, 54 are open, the LPG in the service tank 22 causes the engine 11 and the fuel recovery line 41 and / or the first It circulates through the bypass line 51 or the second bypass line 53 to the service tank 22.

As described above, when the temperature of the LPG in the service tank 22 is 0 ° C., the pressure of the base layer of the service tank 22 (saturated vapor pressure of the LPG) is about 0.4 MPa, while LPG is used as fuel. The required pressure of the engine 11 is 5.0 to 6.0 MPa. When the pressure of the base layer in the service tank 22 is less than a predetermined value, even if the engine 11 is to be operated as LPG as fuel, the supply pressure of LPG from the pump 32 cannot be raised to the required pressure. , It is not possible to drive the engine 11 with LPG. Until the required pressure can be reached (until the pressure in the base layer exceeds a predetermined value), since the engine 11 cannot be driven using LPG, the operation of the engine 11 using LPG cannot be performed. Initiation is delayed as much.

As described above, the control device 6 uses LPG through the engine 11 and / or the first bypass line 51 or the second bypass line 53 during the period when LPG is not used as fuel. By circulating, the temperature of the LPG increases at least by heat input from the pump 32. In the case of a binary fuel engine, when the engine 11 is operated using fuel oil, the LPG passes through the engine 11 and circulates to receive heat from the engine 11, thereby making it easy to increase the temperature of the LPG. Further, according to this embodiment, since the heater 33 is disposed between the pump 32 and the branch point of the first bypass line 51 on the fuel supply line 31, the first bypass line 51 Even when LPG is circulated through, the temperature of LPG can be increased by the heater 33. Since the cooler 44 is a temperature controller that controls the temperature of the LPG at a lower temperature than the heater 33, when the LPG is circulated at a low pressure, the temperature of the LPG is lower than the temperature of the cooler 44. Therefore, the "cooler 44" can function as a heater.

By the circulation of LPG, the temperature of LPG in the service tank 22 rises, and accordingly, the pressure of the base layer in the service tank 22 (saturated vapor pressure of LPG) also increases. When the pressure of the base layer exceeds a predetermined value, the pump 32 is stopped and the circulation of LPG is stopped. Here, in order to prevent the operation and stop of the pump 32 from being repeated frequently, the threshold value of the circulation stop determination may be set to a value greater than the threshold value of the circulation start determination (high pressure value).

The rotational speed of the pump 32 is not particularly limited, but may be constant at the lowest rotational speed, or may be variable in response to the pressure of the base layer to be detected. By increasing the rotation speed of the pump 32 when the pressure of the base layer is low, the temperature can be increased early.

As described above, when the use of LPG is stopped, the pressure of the base layer in the service tank 22 is maintained at a predetermined value or higher, so when the LPG is started to be used as fuel, the pump 32 supplies the LPG supply pressure. The pressure can be raised to the required pressure in the engine 11, and the operation of the engine using LPG can be smoothly and quickly started.

(Second example)

2 is a schematic configuration diagram of a ship 101 according to the second embodiment. 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 base layer in the service tank 22 detected by the first pressure gauge 71 is equal to or less than a predetermined value when the LPG is stopped. The LPG in the service tank 22 is circulated to the service tank 22 through the engine 11. In this embodiment, as in the first embodiment, when LPG is started to be used as fuel, the supply pressure of LPG from the pump 32 can be increased to the pressure required by the engine 11, and an engine using LPG is used. Can start smoothly and quickly.

(Modified example)

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

Further, the predetermined values (V, V ') do not always have to be constant, and the control device 6 increases the predetermined values (V, V') when the number of revolutions of the pump 32 reaches the lowest number of revolutions. You may want to For example, in the configuration shown in Fig. 1, the predetermined value V may be increased to a flow rate within a range from 1.1 x Qe to 11.0 x Qe. Alternatively, in the configuration shown in Fig. 3, the predetermined value V 'may be increased to a flow rate within a range from 0.1 x Qe to 10.0 x Qe.

When the rotational speed of the pump 32 reaches the minimum rotational speed, the predetermined values V and V 'are constant, and when the flow control valve 54 provided in the second bypass line 53 is opened, The surplus obtained by subtracting predetermined values (V, V ') from the discharge flow rate (Q) of the pump (32) is conveyed to the service tank (22) through the second bypass line (53). Since the surplus is receiving heat from the pump 32, the temperature of the LPG in the service tank 22 rises. On the other hand, when a predetermined value (V, V ') is increased when the rotational speed of the pump 32 reaches the minimum rotational speed, LPG conveyed to the service tank 22 through the second bypass line 53 is reduced. I can do it. On the other hand, LPG passing through the engine 11 also increases by increasing the predetermined values V and V ', but such an increase is cooled by the cooler 44 installed in the fuel recovery line 41. Therefore, the temperature rise of LPG in the service tank 22 can be suppressed.

In the above embodiment, although the fuel tank 2 is composed of the storage tank 21 and the service tank 22, the storage tank 21 is omitted, and the fuel tank 2 is composed of only the service tank 22 good. That is, LPG may be introduced directly from the LPG supply source into the service tank 22. However, if the same configuration as in the above embodiment, the fuel tank 2 can be divided into a storage tank 21 for LPG introduction and a service tank 22 for LPG circulation.

Since the pressure (saturated vapor pressure) of the base layer in the service tank 22 depends on the temperature in the service tank 22, the temperature in the service tank 22 instead of the first pressure gauge 71 (the temperature of the base layer is also the liquid layer temperature) It is also possible to provide a thermometer for detecting) and determine whether or not the pump 32 needs to operate in response to the temperature detected by the thermometer.

1, 101, 201: Ship
11: propulsion engine
2: fuel tank
6: Control device
31: fuel supply line
32: Pump
41: fuel recovery line
51, 251: Bypass line
61: No pump operation command
71: first pressure gauge

Claims (3)

A fuel tank storing LPG so that the temperature of the LPG changes in accordance with the atmospheric temperature;
A propulsion engine using LPG as fuel,
A fuel supply line for supplying LPG from the fuel tank to the engine,
A pump installed 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 base layer in the fuel tank,
It has a control device for controlling the number of revolutions of the pump,
The control device is configured to circulate LPG in the fuel tank through the engine to the fuel tank by operating the pump when the pressure detected by the pressure gauge is equal to or less than a predetermined value during a period when LPG is not used as fuel. Ship characterized by.
A fuel tank storing LPG so that the temperature of the LPG changes in accordance with the atmospheric temperature;
A propulsion engine using LPG as fuel,
A fuel supply line for supplying LPG from the fuel tank to the engine,
A pump installed 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 on the downstream side of the pump and connected to the fuel recovery line or the fuel tank,
A pressure gauge for detecting the pressure of the base layer in the fuel tank,
It has a control device 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 when LPG is not used as fuel, the control device operates the pump to supply LPG in the fuel tank to one or more of the engine and the bypass line. Vessel characterized in that it circulates through the fuel tank.
A fuel tank storing LPG so that the temperature of the LPG changes in accordance with the atmospheric temperature;
A propulsion engine using LPG as fuel,
A fuel supply line for supplying LPG from the fuel tank to the engine,
A pump installed in the fuel supply line,
An LPG temperature and pressure management method applied to a ship having a fuel recovery line for recovering LPG that is not used as the fuel tank from the engine,
In the period when LPG was not used as fuel, the condition that the pressure of the base layer in the fuel tank was lower than the predetermined value, the condition that the temperature of the LPG in the fuel tank was lower than the predetermined value, and that the pump operation command member was operated by the crew LPG temperature and pressure management method, characterized in that when one or more of the conditions are met, the pump is operated to circulate the LPG in the fuel tank through the engine to the fuel tank.

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