CN112638763B

CN112638763B - ship

Info

Publication number: CN112638763B
Application number: CN201980058116.1A
Authority: CN
Inventors: 野崎拓海; 髙木俊宏; 武田宏之; 赤星显悟; 吉村崇; 萩原和也; 宍粟雄辉; 安部崇嗣; 成岛直树
Original assignee: Kawasaki Jukogyo KK
Current assignee: Kawasaki Motors Ltd
Priority date: 2018-09-06
Filing date: 2019-09-06
Publication date: 2023-08-22
Anticipated expiration: 2039-09-06
Also published as: JPWO2020050404A1; WO2020050404A1; KR20210048520A; JP7049469B2; KR102404713B1; SG11202102112QA; CN112638763A

Abstract

A ship is provided with: the device comprises a propulsion engine using LPG as fuel, a service storage tank connected with the propulsion engine through a supply pipeline and a return pipeline and storing the LPG, a storage tank connected with the service storage tank through a transfer pipeline and storing the LPG with lower temperature than the LPG in the service storage tank, a pump arranged on the supply pipeline and a heater arranged on the transfer pipeline and heating the LPG supplied from the storage tank to the service storage tank in a mode that the temperature of the LPG in the service storage tank is higher than the atmospheric temperature.

Description

Ship

Technical Field

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

Background

In a conventional ship, the fuel of the propulsion engine is usually fuel oil such as heavy oil or LNG (Liquefied Natural Gas; liquefied natural gas). In recent years, LPG (Liquefied Petroleum Gas; liquefied petroleum gas) has been proposed as a fuel for propulsion engines.

For example, patent document 1 discloses a ship in which LPG is supplied from a fuel tank to a propulsion engine while maintaining the liquid. When LPG is used as fuel, there is an advantage that a sulfur oxide solution is not required and carbon dioxide emissions are small compared to fuel oil, and there is an advantage that the specific gravity is large and thus the fuel tank can be miniaturized compared to LNG.

Prior art literature:

patent literature

Patent document 1: korean laid-open patent publication No. 2012-013398.

Disclosure of Invention

Problems to be solved by the invention:

when LPG is used as fuel, it is considered that the fuel tank and the propulsion engine are connected by a supply line and a return line, the LPG is circulated between the fuel tank and the engine, and only a necessary amount is used in the engine.

In the case of circulating LPG as described above, the LPG is heated while passing through the engine. Thus, it is desirable that the fuel tank be divided into a service (service) tank for LPG circulation and a storage (storage) tank for LPG maintenance. In this case, the service tank stores LPG at a relatively high temperature and the storage tank stores LPG at a relatively low temperature.

At least the service tank among the storage tank and the service tank is a pressure vessel resistant to high pressure, and even if the temperature of the LPG in the service tank is above atmospheric temperature, the balance of the LPG can be maintained by the high pressure in the service tank.

The temperature of the LPG in the storage tank may be equal to or lower than the saturation temperature at atmospheric pressure, or the storage tank may be a pressure vessel in the same manner as the service tank, and the LPG may be kept in a balanced state by the high pressure in the storage tank. An amount of LPG corresponding to the fuel consumption of the engine is supplied from the storage tank to the service tank through a transfer line connecting them.

The above-mentioned supply line is provided with a pump. It is assumed that in case the temperature of the LPG in the service tank is lower than the atmospheric temperature, the LPG may be vaporized at the inlet of the pump by heating from the atmosphere when flowing in the supply line from the service tank to the pump. In this case, breakage of the pump and performance degradation occur. For example, when LPG having a temperature lower than the atmospheric temperature is supplied from the storage tank to the service tank, the temperature of the LPG in the service tank may be lower than the atmospheric temperature.

Accordingly, an object of the present invention is to provide a ship capable of preventing evaporation of LPG at an inlet of a pump provided in a supply line.

Means for solving the problems:

in order to solve the above problems, a ship according to an aspect of the present invention includes: the device comprises a propulsion engine using LPG as fuel, a service storage tank connected with the propulsion engine through a supply pipeline and a return pipeline and storing the LPG, a storage tank connected with the service storage tank through a transfer pipeline and storing the LPG with lower temperature than the LPG in the service storage tank, a pump arranged on the supply pipeline and a heater arranged on the transfer pipeline and heating the LPG supplied from the storage tank to the service storage tank in a mode that the temperature of the LPG in the service storage tank is higher than the atmospheric temperature.

According to the above configuration, the shortage of the heating amount of the LPG in the heater can be suppressed, and the temperature of the LPG in the service tank can be reduced from the atmospheric temperature. Thereby, vaporization of LPG at the inlet of the pump can be prevented.

For example, the ship may further include a control device for adjusting the heating amount of the LPG in the heater so that the temperature of the LPG in the service tank is higher than the atmospheric temperature.

For example, the ship may further include: a bypass line branching from the transfer line on an upstream side of the heater and merging with the transfer line on a downstream side of the heater, and a distribution mechanism for changing a ratio of a flow rate of the LPG passing through the heater to a flow rate of the LPG flowing through the bypass line; the control device controls the distribution mechanism to adjust the heating amount of the LPG in the heater.

The ship may further include: a cooler provided in the return line and configured to cool the LPG returned from the propulsion engine to the service tank; the control device adjusts not only the heating amount of the LPG in the heater but also the cooling amount of the LPG in the cooler in such a manner that the temperature of the LPG in the service tank is higher than the atmospheric temperature. According to this structure, the LPG returned from the engine to the service tank is cooled by the cooler, so that the temperature of the LPG in the service tank can be suppressed from excessively increasing. Further, by adjusting the heating amount of LPG and the cooling amount of LPG, a wide range of conditions can be handled.

A ship according to another aspect of the present invention is characterized by comprising: the device comprises a propulsion engine using LPG as fuel, a service storage tank connected with the propulsion engine through a supply pipeline and a return pipeline and storing the LPG, a storage tank connected with the service storage tank through a transfer pipeline and storing the LPG with lower temperature than the LPG in the service storage tank, a pump arranged on the supply pipeline and a cooler arranged on the return pipeline and cooling the LPG returned from the propulsion engine to the service storage tank in a mode that the temperature of the LPG in the service storage tank is higher than the atmospheric temperature.

According to the above configuration, the LPG returned from the engine to the service tank is cooled by the cooler, so that the temperature of the LPG in the service tank can be suppressed from excessively increasing. Further, according to the above configuration, the cooling amount of the LPG in the cooler is suppressed from becoming excessive, and the temperature of the LPG in the service tank is lower than the atmospheric temperature. Thereby, vaporization of LPG at the inlet of the pump can be prevented.

For example, the ship may further include: and a control device for adjusting the cooling amount of the LPG in the cooler in such a manner that the temperature of the LPG in the service tank is higher than the atmospheric temperature.

The invention has the following effects:

according to the present invention, vaporization of LPG provided at the inlet of the pump of the supply line can be prevented.

Drawings

Fig. 1 is a schematic configuration view of a ship according to an embodiment of the present invention;

fig. 2 is a schematic configuration diagram of a modified ship;

fig. 3 is a schematic configuration view of the ship according to the first alternative means;

FIG. 4 is an enlarged view of a service tank of the first alternative;

FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4;

FIG. 6 is an enlarged view of a service tank of a second alternative;

fig. 7 is a schematic configuration view of a ship according to a third alternative means;

fig. 8 is a schematic configuration view of a ship according to a fourth alternative means;

FIG. 9 is an enlarged view of a fourth alternative service tank;

fig. 10 is an enlarged view of a service tank according to a modification of the fourth alternative means.

Detailed Description

Fig. 1 shows a vessel 1 according to an embodiment of the invention. The ship 1 includes an LPG-fueled propulsion engine 11, a storage tank 2 for storing LPG, and a service tank 4.LPG may be propane gas containing propane as a main component or butane gas containing butane as a main component.

The engine 11 is connected to the service tank 4 via a supply line 5 and a return line 6. In other words, between the service tank 4 and the engine 11, the LPG circulates through the supply line 5 and the return line 6. The service tank 4 is connected to the storage tank 2 via a transfer line 3. For example, the volume of the storage tank 2 is larger than the volume of the service tank 4.

The engine 11 is a piston engine such as a Diesel Cycle (Diesel Cycle) or an Otto Cycle (Otto Cycle). Although not shown, the engine 11 includes a main flow passage connecting the downstream end of the supply line 5 and the upstream end of the return line 6, and a plurality of fuel injection valves connected in parallel with the main flow passage. The fuel injection valve injects LPG into the air supplied to the cylinder while maintaining the LPG in a liquid state. However, the engine 11 may also be a gas turbine engine.

The supply line 5 is provided with a pump 51, a heater 52, and a shutoff valve 53 in this order from the upstream side. The number of the pumps 51 may be 1 or more. The heater 52 heats the LPG supplied from the service tank 4 to the engine 11 to a required temperature (for example, 45 ℃) of the engine 11. The upstream end of the supply line 5 is connected to the lower part of the service tank 4. For example, the heater 52 is a heat exchanger that exchanges heat between a heating medium fluid and LPG.

The return line 6 is provided with a shutoff valve 61, a first pressure adjusting valve 62, a cooler 63, and a second pressure adjusting valve 64 in this order from the upstream side. The positions of the shutoff valve 61 and the first pressure adjustment valve 62 may be reversed. The cooler 63 cools the LPG returned from the engine 11 to the service tank 4 (by the LPG heated by the engine 11) to a predetermined temperature (for example, 40 ℃). In addition, the cooler 63 may be omitted. The return line 6 extends to the interior of the service tank 4. For example, the cooler 63 is a heat exchanger that exchanges heat between the heat medium fluid and LPG.

In the present embodiment, the supply line 5 and the return line 6 are connected by a bypass line 71. The bypass line 71 branches off from the supply line 5 between the heater 52 and the shutoff valve 53, and merges with the return line 6 between the first pressure adjusting valve 62 and the cooler 63. The bypass line 71 is provided with a shutoff valve 72. However, a flow control valve may be provided in place of the shutoff valve 72 in the bypass line 71.

The service tank 4 is a pressure vessel resistant to high pressure. The service tank 4 is not covered with a heat insulating material, and the temperature of the LPG in the tank 4 changes according to the atmospheric temperature, the temperature of the LPG supplied from the storage tank 2, the temperature of the LPG returned from the engine 11, and the like. That is, the equilibrium state of the LPG is maintained by the high pressure in the service tank 4. For example, assuming a temperature of 0-50 ℃ for the LPG in the service tank 4, the pressure of the gas layer (saturated vapor pressure) in the service tank 4 is about 0.4MPa to about 1.8MPa at the gauge pressure. Hereinafter, the pressure is expressed as a gauge pressure. However, the service tank 4 may also be covered by an insulating material.

On the other hand, the storage tank 2 is covered with a heat insulating material (not shown) in order to maintain the LPG in the interior at a low temperature. The low temperature may be a saturation temperature at atmospheric pressure (at-42 ℃ C. In propane gas) or lower or higher if it is lower than the temperature of the LPG in the service tank 4 (more preferably, the atmospheric temperature). However, the storage tank 2 may be a pressure vessel as with the service tank 4, and the equilibrium state of the LPG is maintained by the high pressure in the storage tank 2.

A pump 21 is disposed in the storage tank 2. The number of the pumps 21 may be 1 or more. The upstream end of the transfer line 3 is connected to a pump 21. The transfer line 3 extends to the interior of the service tank 4. However, the pump 21 may be provided in the middle of the transfer line 3 outside the storage tank 2.

An amount of LPG corresponding to the fuel consumption of the engine 11 is supplied from the storage tank 2 to the service tank 4 through the transfer line 3. The supply of the LPG may be continuous or intermittent. The transfer line 3 is provided with a heater 32 for heating the LPG supplied from the storage tank 2 to the service tank 4 to a predetermined temperature (for example, 0 to 45 ℃). For example, the heater 32 is a heat exchanger that exchanges heat between a heating medium fluid and LPG.

In the present embodiment, a bypass line 33 for bypassing the heater 32 is connected to the transfer line 3. The bypass line 33 branches off from the transfer line 3 on the upstream side of the heater 32, and merges with the transfer line 3 on the downstream side of the heater 32.

A first flow control valve 31 is provided between the branching point of the bypass line 33 of the transfer line 3 and the heater 32, and a second flow control valve 34 is provided in the bypass line 33. The first flow control valve 31 and the second flow control valve 34 constitute a distribution mechanism 35 for changing the ratio of the flow rate of the LPG passing through the heater 32 to the flow rate of the LPG flowing through the bypass line 33.

However, instead of the first flow rate control valve 31 and the second flow rate control valve 34, a distribution valve (three-way valve) provided at a branching point of the bypass line 33 of the transfer line 3 may be used as the distribution mechanism 35.

The pump 51 and various valves are controlled by the control device 8. However, in fig. 1, only a part of the signal lines are drawn for the sake of simplicity of the drawing. The control device 8 is a computer having a Memory such as a ROM (Read-Only Memory) and a RAM (Random Access Memory ) and a CPU (Central Processing Unit, central processing unit), and a program stored in the ROM is executed by the CPU. The control device 8 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).

As for the shutoff valves 53, 61, the control device 8 closes the shutoff valves 53, 61 during the stop of the engine 11, and opens the shutoff valves 53, 61 during the operation of the engine 11. During the stop of the engine 11, the flow path between the shutoff valves 53, 61 (the downstream side portion of the supply line 5, the main flow path of the engine 11, and the upstream side portion of the return line 6) is purged with the inert gas.

The control device 8 controls the pump 51 so that the discharge flow rate of the pump 51 changes according to the fuel consumption of the engine 11. For example, when the load on the engine 11 is high, the surplus flow rate, which is the flow rate of the LPG flowing from the engine 11 into the return line 6, is detected by a flow meter, which is not shown, and the pump 51 is controlled so that the surplus flow rate is in a constant ratio with respect to the fuel consumption of the engine 11. Instead of the surplus flow rate, a supply flow rate that is a flow rate of LPG flowing from the supply line 5 into the engine 11 may be used. Conversely, when the load on the engine 11 is low, the discharge flow rate of the pump 51 is kept constant.

As for the shutoff valve 72, the control device 8 opens the shutoff valve 72 and closes the shutoff valve 53 until the flow rate of the pump 51 stabilizes before the engine 11 is operated. When the flow rate of the pump 51 is stabilized, the control device 8 closes the shutoff valve 72 and opens the shutoff valve 53. When the engine supply pressure (pressure detected by a first pressure gauge 91 described later) increases due to an abrupt decrease in the load of the engine 11 during the operation of the engine 11, the control device 8 opens the shutoff valve 72 to suppress the increase in the engine supply pressure.

The control device 8 is electrically connected to the first pressure gauge 91 and the second pressure gauge 92. The first pressure gauge 91 is provided in the supply line 5 downstream of the branching point of the bypass line 71, and detects the pressure of the LPG supplied to the engine 11. The second pressure gauge 92 is provided in the return line 6 between the first pressure regulating valve 62 and the second pressure regulating valve 64, and detects the pressure of the LPG depressurized by the first pressure regulating valve 62.

The control device 8 controls the first pressure adjustment valve 62 so that the pressure detected by the first pressure gauge 91 becomes the required pressure of the engine 11 (for example, 5 to 6MPa in the case where the engine 11 is a piston engine of a diesel cycle).

As described above, since the LPG is heated by the engine 11, the temperature of the LPG flowing from the engine 11 into the return line 6 is slightly increased (for example, 55 ℃). Therefore, in order to prevent the LPG depressurized by the first pressure regulating valve 62 from vaporizing, the control device 8 controls the second pressure regulating valve 64 so that the pressure detected by the second pressure gauge 92 becomes a set value (for example, 3.5 MPa) higher than the saturation vapor pressure at the envisaged maximum temperature.

The control device 8 is also electrically connected to the first thermometer 81 and the second thermometer 82. The first thermometer 81 detects the atmospheric temperature. The second thermometer 82 is provided in the service tank 4, and detects the temperature of the LPG in the service tank 4.

The control device 8 controls the first flow rate control valve 31 and the second flow rate control valve 34 (the distribution mechanism 35) so that the temperature of the LPG in the service tank 4 detected by the second thermometer 82 is higher than the atmospheric temperature detected by the first thermometer 81, and adjusts the heating amount of the LPG in the heater 32. Instead of using the first thermometer 81, an estimated value such as weather forecast may be used as the atmospheric temperature.

As described above, in the ship 1 according to the present embodiment, since the heating amount of the LPG in the heater 32 is appropriately adjusted, it is possible to suppress the shortage of the heating amount of the LPG in the heater 32 and the temperature of the LPG in the service tank 4 from being lower than the atmospheric temperature. Thereby, vaporization of LPG at the inlet of the pump 51 can be prevented.

In the present embodiment, since the LPG returned from the engine 11 to the service tank 4 is cooled by the cooler 63, it is possible to suppress the temperature of the LPG in the service tank 4 from becoming excessively high.

(modification)

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

For example, instead of the second thermometer 82 provided in the service tank 4, as shown in fig. 2, a second thermometer 83 provided in the transfer line 3 may be employed. The second thermometer 83 detects a transfer temperature, which is a temperature at which the LPG flowing through the bypass line 33 and the LPG passing through the heater 32 are mixed.

In this case, the control device 8 first calculates a return flow rate, which is a flow rate of the LPG flowing from the return line 6 into the service tank 4, a transfer flow rate, and a target transfer temperature; the transfer flow rate is the flow rate of LPG flowing from the transfer line 3 into the service tank 4; the target transfer temperature is a temperature required to raise the temperature of the LPG in the service tank 4 from the atmospheric temperature to a temperature higher than the atmospheric temperature. The control device 8 controls the first flow rate control valve 31 and the second flow rate control valve 34 (the distribution mechanism 35) so that the transfer temperature detected by the second thermometer 83 becomes the target transfer temperature.

The heater 32 is a heat exchanger that exchanges heat between the heat medium fluid and the LPG, and when the temperature of the heat medium fluid supplied to the heater 32 can be changed, the bypass line 33 and the flow control valves 31 and 34 may be omitted, and the control device 8 adjusts the heating amount of the LPG in the heater 32 by changing the temperature of the heat medium fluid supplied to the heater 32.

The control device 8 may adjust not only the heating amount of the LPG in the heater 32 but also the cooling amount of the LPG in the cooler 63 so that the temperature of the LPG in the service tank 4 becomes higher than the atmospheric temperature. Thus, by adjusting the heating amount of LPG and the cooling amount of LPG, a wide range of conditions can be handled.

When the cooling amount of the LPG in the cooler 63 is adjusted, although not shown, a bypass line may be connected to the return line 6 so as to bypass the cooler 63, and the cooling amount of the LPG in the cooler 63 may be adjusted by changing the ratio of the flow rate of the LPG passing through the cooler 63 to the flow rate of the LPG flowing through the bypass line. Alternatively, the cooler 63 is a heat exchanger that exchanges heat between the heat medium fluid and the LPG, and when the temperature of the heat medium fluid supplied to the cooler 63 can be changed, the cooling amount of the LPG in the cooler 63 can be adjusted by changing the temperature of the heat medium fluid supplied to the cooler 63.

In the case of adjusting not only the heating amount of the LPG in the heater 32 but also the cooling amount も of the LPG in the cooler 63, for example, the heating amount of the LPG in the heater 32 can be made smaller and the cooling amount of the LPG in the cooler 63 can be made smaller than the case of adjusting only with the heater 32.

The control device 8 may also adjust only the cooling amount of the LPG in the cooler 63 without adjusting the heating amount of the LPG in the heater 32 in such a manner that the temperature of the LPG in the service tank 4 is higher than the atmospheric temperature. According to this configuration, the cooling amount of the LPG in the cooler 63 is suppressed from becoming excessive, and the temperature of the LPG in the service tank 4 is lower than the atmospheric temperature. Thereby, vaporization of LPG at the inlet of the pump 51 can be prevented. Obviously, the heater 32 may be omitted in the case of adjusting only the cooling amount of the LPG in the cooler 63.

In fig. 1 and 2, the service tank 4 has a vertically long cylindrical shape, and the service tank 4 may have other shapes such as a horizontally long cylindrical shape, a spherical shape, a cubic shape, and a rectangular parallelepiped shape. Similarly, the shape of the storage tank 2 may be arbitrarily changed. These points are also similar to those of the alternative means described later.

(alternative means)

In the above embodiment, in order to prevent the evaporation of the LPG at the inlet of the pump 51, means for increasing the temperature of the LPG in the service tank 4 to be higher than the atmospheric temperature is used. However, other means may be employed in order to prevent vaporization of LPG at the inlet of the pump 51.

Within the service tank 4, relatively low temperature LPG (supply LPG) supplied through the transfer line 3 is mixed with relatively high temperature LPG (return LPG) returned through the return line 6. However, before the supply LPG and the return LPG are completely mixed, the relatively high temperature return LPG may be vaporized at the inlet of the pump 51 provided to the supply line 5 when the return LPG is discharged from the service tank 4 through the supply line 5. In this case, breakage of the pump 51 and performance degradation occur.

Therefore, the first to fourth substitution means described below are considered from the above point of view. In the first to fourth alternative means, the same reference numerals are given to the same constituent elements as those in the above-described embodiment, and redundant description thereof is omitted.

(first alternative means)

Fig. 3 shows a vessel 1A according to a first alternative. The ship 1A differs from the ship 1 shown in fig. 1 in that the bypass line 33, the first flow control valve 31, and the second flow control valve 34 are not included. However, the vessel 1A may include the bypass line 33, the first flow rate control valve 31, and the second flow rate control valve 34 as in the above embodiment, and the first flow rate control valve 31 and the second flow rate control valve 34 may be controlled as in the above embodiment. In the first alternative, there is a special countermeasure for the service tank 4.

When the service tank 4 is described in more detail with reference to fig. 4 and 5, the downstream side portion of the return line 6 extending from the outside of the service tank 4 to the inside and the downstream side portion of the transfer line 3 extending from the outside of the service tank 4 are configured in such a manner that the LPG flowing out from the downstream end of the return line 6 and the downstream end of the transfer line 3 forms a swirl flow.

In the first alternative means, a mortar-like (rounded conical) guide member 45 having a diameter reduced downward is disposed in the service tank 4 (in the liquid layer 40 made of LPG, to be precise). The downstream end of the return line 6 and the downstream end of the transfer line 3 are located above the guide member 45, and the upstream end of the supply line 5 is connected to the service tank 4 below the guide member 45.

The downstream side portion of the return line 6 is slightly bent downward with respect to the circumferential direction of the guide member 45, that is, the horizontal direction, in such a manner that the LPG flowing out from the downstream end of the return line 6 collides obliquely against the upper surface of the guide member 45. Similarly, the downstream side portion of the transfer line 3 is slightly bent downward with respect to the circumferential direction of the guide member 45, that is, the horizontal direction, in such a manner that the LPG flowing out from the downstream end of the transfer line 3 collides obliquely against the upper surface of the guide member 45. Therefore, the LPG flowing out from the downstream end of the return line 6 and the downstream end of the transfer line 3 forms a swirl flow along the upper surface of the guide member 45.

In the ship 1A of the above-described structure, the relatively high-temperature return LPG (LPG returned to the service tank 4 through the return line 6) and the relatively low-temperature supply LPG (LPG supplied to the service tank 4 through the transfer line 3) are mixed by spin-flow. Thereby, the temperature of the LPG in the service tank 4 is uniform, and vaporization of the LPG at the inlet of the pump 51 can be prevented.

(modification)

In the first alternative, the guide member 45 is disposed in the service tank 4, but the guide member 45 may be omitted when the downstream side portion of the return line 6 and the downstream side portion of the transfer line 3 are bent in the horizontal direction, which is the circumferential direction of the guide member 45. However, if the guide member 45 is provided as the first alternative, a spin back flow can be formed above the guide member 45.

(second alternative means)

Next, a ship according to a second alternative means will be described with reference to fig. 6. The second alternative vessel differs from the first alternative vessel 1A only in the construction within the service tank 4.

Specifically, in the second alternative, the downstream end of the return line 6 is located below the downstream end of the transfer line 3 within the service tank 4.

In the second alternative, the partition member 46 is disposed in the service tank 4. The partition member 46 divides the liquid layer 40 (the gas layer is composed of PG vaporized from LPG) composed of LPG into the first region 41 and the second region 42. The upstream end of the supply line 5 communicates with the first region 41, and the downstream end of the return line 6 and the downstream end of the transfer line 3 are located in the second region 42.

In the second alternative, the partition member 46 is a plate parallel to the vertical direction, and the first region 41 and the second region 42 are arranged in the horizontal direction. However, the partition member 46 may be a plate parallel to the horizontal direction, and the first region 41 may be located on the lower side of the second region 42. In this case, the partition member 46 may be a porous plate such as a mesh material or a perforated metal plate. Alternatively, the partition member 46 may be a tube shape extending in the vertical direction so that the first region 41 is located at the center of the service tank 4 and the second region 42 is located around the first region 41.

In the structure of the second alternative means, the return LPG rises and the supply LPG falls in the service tank 4 as indicated by the arrow in fig. 6 by the density difference between the return LPG of a relatively high temperature and the supply LPG of a relatively low temperature. Thus, the return LPG and the supply LPG are mixed by convection. This makes it possible to prevent the LPG at the inlet of the pump 51 from vaporizing while keeping the LPG in the service tank 4 at a uniform temperature.

(modification)

Even without the partition member 46, the return LPG and the supply LPG can be mixed by convection, and thus the partition member 46 can be omitted. However, if the partition member 46 is provided, the return LPG and the supply LPG can be sufficiently mixed in the second region 42.

(third alternative means)

Fig. 7 shows a vessel 1B according to a third alternative. In the third alternative, the return line 6 and the transfer line 3 merge with each other outside the service tank 4. Therefore, the downstream side portion of the return line 6 and the downstream side portion of the transfer line 3 form a common flow path extending from the outside to the inside of the service tank 4.

More specifically, the return line 6 merges with the transfer line 3 on the downstream side of the second pressure adjustment valve 64. The return line 6 is provided with a check valve 65 between the second pressure regulating valve 64 and the junction point of the transfer line 3.

The transfer line 3 merges with the return line 6 on the downstream side of the heater 32. In the transfer line 3, a check valve 36 is provided between the heater 32 and the junction point of the return line 6.

The return line 6 and the transfer line 3 may be connected in a T-shape or a Y-shape in a confluence manner. Alternatively, a container is provided at the junction point of the return line 6 and the transfer line 3, and three pipes are connected to the container.

In the ship 1B of the above-described structure, the relatively high-temperature return LPG and the relatively low-temperature supply LPG are mixed with each other and then flow into the service tank 4. This makes it possible to prevent the LPG at the inlet of the pump 51 from vaporizing while keeping the LPG in the service tank 4 at a uniform temperature.

(fourth alternative means)

Fig. 8 shows a vessel 1C according to a fourth alternative. The vessel 1C includes a bypass line 33, a first flow control valve 31, and a second flow control valve 34, as in the above-described embodiment. As described in the above embodiment, the first flow rate control valve 31 and the second flow rate control valve 34 constitute a distribution mechanism 35 for changing the ratio of the flow rate of the LPG passing through the heater 32 to the flow rate of the LPG flowing through the bypass line 33.

In the fourth alternative, there is a special countermeasure for servicing the tank 4. When the service tank 4 is described in more detail with reference to fig. 9, the downstream end of the transfer line 3 is located below the downstream end of the return line 6 in the service tank 4. The upstream end of the supply line 5 is connected to the service tank 4 below the downstream end of the transfer line 3.

In the fourth alternative, a partition member 47 is disposed in the service tank 4. The partition member 47 divides the liquid layer 40 (the gas layer is composed of PG vaporized from LPG) composed of LPG into the first region 41 and the second region 42. The upstream end of the supply line 5 communicates with the first region 41, the downstream end of the transfer line 3 is located in the first region 41, and the downstream end of the return line 6 is located in the second region 42.

In the fourth alternative, the partition member 47 is a horizontal perforated plate, the first region 41 is a region on the lower side of the partition member 47, and the second region 42 is a region on the upper side of the partition member 47. As such a porous plate, for example, a mesh material, a perforated metal plate, or the like can be used.

The control device 8 is electrically connected to the first thermometer 84 and the second thermometer 85. The first thermometer 84 is provided in the service tank 4, and detects the temperature of the upper portion (in the present embodiment, the second region 42) of the liquid layer 40 in the service tank 4. The temperature of the upper portion of the liquid layer 40 is lower than the temperature of the liquid surface in the service tank 4 due to the influence of the temperature distribution (density distribution) in the service tank 4. The second thermometer 85 is provided on the transfer line 3 downstream of the junction point of the bypass line 33, and detects the temperature of the LPG flowing from the transfer line 3 into the service tank 4 (the LPG obtained by mixing the LPG passing through the heater 32 and the LPG flowing through the bypass line 33).

Then, the control device 8 controls the first flow rate control valve 31 and the second flow rate control valve 34 (distribution mechanism 35) so that the temperature of the LPG detected by the second thermometer 85 is kept lower than the temperature of the LPG detected by the first thermometer 84 (the temperature equal to or lower than the temperature of the liquid surface in the service tank 4), and adjusts the heating amount of the LPG in the heater 32.

As described above, in the ship 1C of the fourth alternative, the downstream end of the transfer line 3 in the service tank 4 is located below the downstream end of the return line 6, and therefore, the supply LPG (LPG supplied to the service tank 4 through the transfer line 3) at a lower temperature than the return LPG (LPG returned to the service tank 4 through the return line 6) flows out of the service tank 4 through the supply line 5 preferentially. This prevents the evaporation of LPG at the inlet of the pump 51.

In the fourth alternative means, since the heater 32 is provided in the transfer line 3, the supply LPG can be heated by the heater even when the temperature of the LPG in the storage tank 2 is equal to or lower than the saturation temperature of the atmospheric pressure. Thus, the service tank 4 can be made of a general steel material, not a special steel material for low temperature (for example, a steel material having toughness even at-46 ℃ C. Or lower も). Further, since the heating amount of the supplied LPG is adjusted so that the temperature of the LPG flowing into the service tank 4 from the transfer line 3 is kept lower than the temperature of the upper portion of the liquid layer 40 in the service tank 4, the effect that the supplied LPG at the low temperature flows out preferentially can be reliably obtained even if the heater 32 is provided.

(modification)

The partition member 47 is not necessarily a horizontal porous plate, and may have an inverted L-shaped cross section as shown in fig. 10, or may have another shape. Alternatively, the partition member 47 itself may be omitted.

However, as shown in fig. 9 and 10, the provision of the partition member 47 in the service tank 4 can significantly achieve the effect that the supply LPG flows out preferentially through the supply line.

Symbol description:

1, 1A-1C vessel

11. Engine for propulsion

2. Storage tank

3. Transfer pipeline

32. Heater

33. Bypass pipeline

35. Dispensing mechanism

4. Service storage tank

5. Supply pipeline

51. Pump with a pump body

6. Return line

63. Cooling device

8. And a control device.

Claims

1. A ship, comprising:

an engine for propulsion using LPG as fuel;

a service tank which is connected to the propulsion engine via a supply line and a return line and stores LPG;

a storage tank connected to the service tank through a transfer line and storing LPG at a lower temperature than the LPG in the service tank;

a pump provided in the supply line; and

a heater provided in the transfer line and configured to heat the LPG supplied from the storage tank to the service tank so that the temperature of the LPG in the service tank is higher than the atmospheric temperature;

the equilibrium state of the LPG is maintained by the pressure in the service tank.

2. The ship according to claim 1, further comprising a control device for adjusting the heating amount of the LPG in the heater so that the temperature of the LPG in the service tank is higher than the atmospheric temperature.

3. The ship according to claim 2, further comprising: a bypass line branching from the transfer line on an upstream side of the heater and merging with the transfer line on a downstream side of the heater, and

a distribution mechanism for changing the ratio of the flow rate of the LPG passing through the heater to the flow rate of the LPG flowing through the bypass line;

the control device controls the distribution mechanism to adjust the heating amount of the LPG in the heater.

4. A vessel according to claim 2 or 3, further comprising: a cooler provided in the return line and configured to cool the LPG returned from the propulsion engine to the service tank;

the control device adjusts not only the heating amount of the LPG in the heater but also the cooling amount of the LPG in the cooler in such a manner that the temperature of the LPG in the service tank is higher than the atmospheric temperature.

5. A ship, comprising: an engine for propulsion using LPG as fuel;

a pump provided in the supply line; and

a cooler provided in the return line and configured to cool the LPG returned from the propulsion engine to the service tank so that the temperature of the LPG in the service tank is higher than the atmospheric temperature;

6. The ship according to claim 5, further comprising: and a control device for adjusting the cooling amount of the LPG in the cooler in such a manner that the temperature of the LPG in the service tank is higher than the atmospheric temperature.