CN112638763A

CN112638763A - Ship with a detachable cover

Info

Publication number: CN112638763A
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 Heavy Industries Ltd
Current assignee: Kawasaki Heavy Industries Ltd
Priority date: 2018-09-06
Filing date: 2019-09-06
Publication date: 2021-04-09
Anticipated expiration: 2039-09-06
Also published as: KR20210048520A; JPWO2020050404A1; KR102404713B1; JP7049469B2; CN112638763B; SG11202102112QA; WO2020050404A1

Abstract

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

Description

Ship with a detachable cover

Technical Field

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

Background

In a conventional ship, a fuel for a propulsion engine is generally a fuel oil such as heavy oil or LNG (Liquefied Natural Gas). In recent years, LPG (Liquefied Petroleum Gas) has been proposed as a fuel for propulsion engines.

For example, patent document 1 discloses a ship that supplies LPG maintenance liquid from a fuel tank to a propulsion engine. In the case where LPG is used as a fuel, it has an advantage that a sulfur oxide solution is not required and an amount of carbon dioxide discharged is small as compared with fuel oil, and it has an advantage that a fuel tank can be downsized because it has a large specific gravity as compared with LNG.

Prior art documents:

patent document

Patent document 1: korean laid-open patent publication No. 2012-0113398.

Disclosure of Invention

The problems to be solved by the invention are as follows:

in the case of using LPG as fuel, it is conceivable to connect a fuel tank and a propulsion engine via a supply line and a return line, circulate LPG between the fuel tank and the engine, and use only a necessary amount of LPG in the engine.

In the case where LPG is circulated 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 holding. 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 of the storage tank and the service tank is a high pressure resistant pressure vessel, and even if the temperature of the LPG in the service tank is above the atmospheric temperature, the equilibrium state 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 as in the service tank, and the equilibrium state of the LPG may be maintained by the high pressure in the storage tank. LPG in an amount corresponding to the fuel consumption of the engine is supplied from the storage tank to the service tank through a transfer line connecting the storage tank and the service tank.

The supply line is provided with a pump. Given that the temperature of the LPG in the service tank is lower than the atmospheric temperature, the LPG may vaporize at the inlet of the pump by being heated from the atmosphere as it flows in the supply line from the service tank to the pump. In this case, breakage and performance degradation of the pump 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 vaporization of LPG provided at an inlet of a pump of a supply line.

Means for solving the problems:

in order to solve the above problem, a ship according to an aspect of the present invention includes: the LPG heating system includes a propulsion engine using LPG as fuel, a service tank connected to the propulsion engine through a supply line and a return line and storing 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 heating 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.

According to the above configuration, it is possible to suppress the LPG in the service tank from being lower in temperature than the atmospheric temperature due to insufficient heating amount of the LPG in the heater. Thereby, vaporization of LPG at the inlet of the pump can be prevented.

For example, the above-described 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 off 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 dispensing 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 cooling the LPG returned from the propulsion engine to the service tank; the control means 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 configuration, the LPG returned from the engine to the service tank is cooled by the cooler, and thus the temperature of the LPG in the service tank can be suppressed from increasing excessively. In addition, the LPG heating amount and the LPG cooling amount can be adjusted to cope with a wide range of situations.

Further, according to another aspect of the present invention, there is provided a ship comprising: the LPG cooling system includes a propulsion engine using LPG as fuel, a service tank connected to the propulsion engine through a supply line and a return line and storing 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 cooler provided in the return line and cooling 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.

According to the above configuration, the LPG returned from the engine to the service tank is cooled by the cooler, and thus the temperature of the LPG in the service tank can be suppressed from excessively increasing. Further, according to the above configuration, it is possible to suppress the temperature of the LPG in the service tank from being lower than the atmospheric temperature due to an excessive amount of cooling of the LPG in the cooler. 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 cooling amount of LPG in the cooler in the form that the temperature of LPG in the service storage 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 diagram of a ship according to an embodiment of the present invention;

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

fig. 3 is a schematic configuration diagram of a ship according to a first alternative;

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 the second alternative;

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

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

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

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

Detailed Description

Fig. 1 shows a ship 1 according to an embodiment of the invention. The ship 1 includes a propulsion engine 11 using LPG as fuel, a storage tank 2 storing LPG, and a service tank 4. The LPG may be propane gas containing propane as a main component or propane 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, 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, for example, a piston engine of a Diesel Cycle (Diesel Cycle) or an Otto Cycle (Otto Cycle). Although not shown, the engine 11 includes a main flow path connecting a downstream end of the supply line 5 and an upstream end of the return line 6, and a plurality of fuel injection valves connected in parallel with the main flow path. The fuel injection valve injects LPG in a liquid state into air supplied to the cylinder. 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 shut-off 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 of the engine 11 (e.g., 45 ℃). 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 performs heat exchange between the heat medium fluid and the LPG.

The return line 6 is provided with a shutoff valve 61, a first pressure regulating valve 62, a cooler 63, and a second pressure regulating valve 64 in this order from the upstream side. The positions of the shut-off valve 61 and the first pressure regulating 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 prescribed temperature (e.g., 40 ℃). In addition, the cooler 63 may be omitted. A return line 6 extends to the interior of the service tank 4. The cooler 63 is, for example, a heat exchanger that performs heat exchange between the heat medium fluid and the 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 blocking valve 53, and merges with the return line 6 between the first pressure regulating valve 62 and the cooler 63. The bypass line 71 is provided with a shut-off valve 72. However, a flow control valve may be provided in the bypass line 71 instead of the shut-off valve 72.

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 service tank 4 changes depending on 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. I.e. the equilibrium state of the LPG is maintained by the high pressure in the service tank 4. For example, if the temperature of the LPG in the service tank 4 is assumed to be 0 to 50 ℃, the pressure (saturated vapor pressure) of the gas layer in the service tank 4 is about 0.4MPa to about 1.8MPa under the gauge pressure. Hereinafter, the pressure is represented as a gauge pressure. However, the service tank 4 may also be covered with 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 inside at a low temperature. If the low temperature is lower than the temperature of LPG in the service tank 4 (more preferably, the atmospheric temperature), the low temperature may be equal to or lower than the saturation temperature under atmospheric pressure (minus 42 ℃ in propane gas), or may be higher than the saturation temperature under atmospheric pressure. However, the storage tank 2 may be a pressure vessel as 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.

LPG in an amount 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 LPG may be supplied continuously or intermittently. 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 performs heat exchange between the heat medium fluid and the 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 rate control valve 31 is provided between a branching point of a bypass line 33 of the transfer line 3 and the heater 32, and a second flow rate 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 that changes 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, as the distribution mechanism 35, a distribution valve (three-way valve) provided at a branch point of the bypass line 33 of the transfer line 3 may be used instead of the first flow rate control valve 31 and the second flow rate control valve 34.

The pump 51 and various valves described above are controlled by the control device 8. However, in fig. 1, only a part of the signal lines is shown for simplification of the drawing. The controller 8 is a computer having a Memory such as a ROM (Read-Only Memory) or a RAM (Random Access Memory) and a CPU (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).

Regarding the

shutoff valves

53, 61, the control device 8 closes the

shutoff valves

53, 61 during stop of the engine 11, and opens the

shutoff valves

53, 61 during operation of the engine 11. While the engine 11 is stopped, the flow path between the shutoff valves 53 and 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 in accordance with the fuel consumption of the engine 11. For example, when the load of the engine 11 is high, the remaining flow rate, which is the flow rate of the LPG flowing from the engine 11 into the return line 6, is detected by an unillustrated flow meter, and the pump 51 is controlled so that the remaining flow rate is in a constant ratio to the fuel consumption amount of the engine 11. Instead of the surplus flow rate, a supply flow rate that is the flow rate of LPG flowing from the supply line 5 into the engine 11 may be employed. Conversely, when the load of the engine 11 is low, the discharge flow rate of the pump 51 is kept constant.

Regarding 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 is stabilized before the engine 11 operates. When the flow rate of the pump 51 is stabilized, the control device 8 closes the shut-off valve 72 and opens the shut-off valve 53. When the engine supply pressure (the pressure detected by the first pressure gauge 91 described later) rises due to sudden reduction of the load of the engine 11 during operation of the engine 11, the control device 8 opens the shut-off valve 72 to suppress the rise 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 on the downstream side of the branch point of the first 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 decompressed by the first pressure regulating valve 62.

The controller 8 controls the first pressure regulating 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 diesel-cycle piston engine).

As described above, the LPG is heated by passing through the engine 11, and therefore the temperature of the LPG flowing from the engine 11 into the return line 6 becomes slightly high (for example, 55 ℃). Therefore, in order to prevent vaporization of the LPG decompressed by the first pressure regulating valve 62, 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 saturated vapor pressure at the assumed 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 controller 8 controls the first flow control valve 31 and the second flow control valve 34 (the distribution mechanism 35) so as to adjust the heating amount of the LPG in the heater 32 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. Instead of using the first thermometer 81, an estimated value such as a weather forecast may be used as the atmospheric temperature.

As described above, in the vessel 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 temperature of the LPG in the service tank 4 from being lower than the atmospheric temperature due to the shortage of the heating amount of the LPG in the heater 32. Thereby, vaporization of LPG at the inlet of the pump 51 can be prevented.

In the present embodiment, the LPG returned from the engine 11 to the service tank 4 is cooled by the cooler 63, and therefore, the temperature of the LPG in the service tank 4 can be prevented from becoming excessively high.

(modification example)

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, a second thermometer 83 provided in the transfer pipe 3 may be used as shown in fig. 2. The second thermometer 83 detects a transfer temperature, which is a temperature of LPG obtained by mixing LPG passing through the heater 32 and LPG flowing through the bypass line 33.

In this case, the control device 8 first calculates a return flow rate, which is the 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 make the temperature of the LPG in the service tank 4 higher than the atmospheric temperature from the atmospheric temperature. Then, the controller 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 is changeable, the bypass line 33 and the

flow control valves

31 and 34 may be omitted, and the controller 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. In this way, by adjusting the heating amount of LPG and the cooling amount of LPG, it is possible to cope with a wide range of situations.

When the cooling amount of 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 LPG in the cooler 63 may be adjusted by changing the ratio of the flow rate of LPG passing through the cooler 63 to the flow rate of 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 is changeable, the cooling amount of the LPG in the cooler 63 may be adjusted by changing the temperature of the heat medium fluid supplied to the cooler 63.

When the cooling amount も of the LPG in the cooler 63 is adjusted in addition to the heating amount of the LPG in the heater 32, for example, the heating amount of the LPG in the heater 32 can be reduced and the cooling amount of the LPG in the cooler 63 can be reduced as compared with the case of adjusting only the heater 32.

The control device 8 may adjust only the cooling amount of the LPG in the cooler 63 without adjusting the heating amount of the LPG in the heater 32 so that the temperature of the LPG in the service tank 4 is higher than the atmospheric temperature. With this configuration, the LPG in the service tank 4 can be prevented from being cooled to a temperature lower than the atmospheric temperature due to an excessive amount of cooling of the LPG in the cooler 63. 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 the same in the alternative means described later.

(alternative means)

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

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

Therefore, from the above-described viewpoint, the following first to fourth alternative means are considered. In the first to alternative means, the same components as those of the above-described embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.

(first alternative means)

Fig. 3 shows a vessel 1A according to a first alternative. Unlike the ship 1 shown in fig. 1, this ship 1A does not include the bypass line 33, the first flow control valve 31, and the second flow control valve 34. However, the ship 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 first embodiment, and may control the first flow rate control valve 31 and the second flow rate control valve, as in the above-described embodiment. In the first alternative, a special countermeasure is taken for the service tank 4.

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

In the first alternative, a mortar-shaped (inverted cone-shaped) guide member 45 having a diameter reduced downward is disposed in the service tank 4 (more precisely, in the liquid layer 40 made of LPG). 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 horizontal direction, which is the circumferential direction of the guide member 45, so that the LPG flowing out from the downstream end of the return line 6 obliquely collides with 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 horizontal direction, which is the circumferential direction of the guide member 45, so that the LPG flowing out from the downstream end of the transfer line 3 obliquely collides with the upper surface of the guide member 45. Therefore, the LPG flowing out of the downstream end of the return line 6 and the downstream end of the transfer line 3 forms a swirling flow along the upper surface of the guide member 45.

In the ship 1A having the above-described structure, the relatively high-temperature return LPG (the LPG returned to the service tank 4 through the return line 6) and the relatively low-temperature supply LPG (the LPG supplied to the service tank 4 through the transfer line 3) are mixed by the swirling flow. Thus, 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 example)

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 portion of the return line 6 and the downstream portion of the transfer line 3 are bent in the horizontal direction, which is the circumferential direction of the guide member 45. However, when the guide member 45 is provided as in the first substitute means, the swirling flow can be reliably formed above the guide member 45.

(second alternative means)

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

In the second alternative, a partition member 46 is disposed in the service tank 4. The partition member 46 partitions the liquid layer 40 made of LPG (gas layer is made of PG vaporized by 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, it is also possible that the partition member 46 is parallel to the horizontally oriented plate, and the first region 41 is 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 extending in the vertical direction such that the first region 41 is positioned at the center of the service tank 4 and the second region 42 is positioned around the first region 41.

In the configuration of the second alternative means, the returned LPG rises and the supplied LPG falls in the service tank 4 as shown by the arrows in fig. 6 due to the difference in density between the returned LPG of relatively high temperature and the supplied LPG of relatively low temperature. Thus, the return LPG and the supply LPG are mixed by convection. This makes the temperature of the LPG in the service tank 4 uniform, thereby preventing vaporization of the LPG at the inlet of the pump 51.

(modification example)

Even if the partition member 46 is not provided, the returned LPG and the supplied LPG can be mixed by convection, and therefore, the partition member 46 can be omitted. However, if the partition member 46 is provided, the returned 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 merge with each other outside the service tank 4. Therefore, the downstream portion of the return line 6 and the downstream 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 regulating valve 64. The return line 6 is provided with a check valve 65 between the second pressure regulating valve 64 and the confluence 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 of the return line 6.

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

In the ship 1B having the above-described structure, the return LPG having a relatively high temperature and the supply LPG having a relatively low temperature are mixed with each other and flow into the service tank 4. This makes the temperature of the LPG in the service tank 4 uniform, thereby preventing vaporization of the LPG at the inlet of the pump 51.

(fourth alternative means)

Fig. 8 shows a vessel 1C according to a fourth alternative. The ship 1C includes a bypass line 33, a first flow control valve 31, and a second flow control valve 34, as in the above embodiment. As described in the above embodiment, the first flow control valve 31 and the second flow control valve 34 constitute the distribution mechanism 35 that changes 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 branch point of the bypass line 33 of the transfer line 3 may be used as the distribution mechanism 35.

In the fourth alternative, there is a special countermeasure for the service tank 4. As 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 partitions the liquid layer 40 made of LPG (the gas layer is made of PG vaporized by 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 porous plate, the first region 41 is a region below the partition member 47, and the second region is a region above 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 (the second region 42 in the present embodiment) of the liquid layer 40 in the service tank 4. The temperature of the upper part of the liquid layer 40 is influenced by the temperature distribution (density distribution) in the service tank 4 to a temperature below the liquid surface in the service tank 4. The second thermometer 85 is provided on the transfer line 3 on the downstream side of the junction of the bypass line 33, and detects the temperature of the LPG (LPG obtained by mixing the LPG passed through the heater 32 and the LPG flowing through the bypass line 33) flowing from the transfer line 3 into the service tank 4.

Then, the controller 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 detected by the second thermometer 85 is 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), thereby adjusting the heating amount of the LPG in the heater 32.

As described above, in the vessel 1C of the fourth alternative means, 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 (the LPG supplied to the service tank 4 through the transfer line 3) having a lower temperature than the return LPG (the 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 vaporization 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, even if the temperature of the LPG in the storage tank 2 is equal to or lower than the saturation temperature under atmospheric pressure, the LPG can be heated by the heater. Thus, the service tank 4 can be made of a general steel material without using a special steel material for low temperature (for example, a steel material having toughness even at-46 ℃ C. or lower, でも). Further, since the heating amount of the supplied LPG is adjusted so that the temperature of the LPG flowing from the transfer line 3 into the service tank 4 is kept lower than the temperature of the upper portion of the liquid layer 40 in the service tank 4, even if the heater 32 is provided, the effect that the supplied LPG of the low temperature preferentially flows out can be reliably obtained.

(modification example)

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 475 itself may be omitted.

However, as shown in fig. 9 and 10, if the partition member 47 is disposed in the service tank 4, the effect of preferentially flowing out the supply LPG through the supply line can be remarkably obtained.

Description of the symbols:

1, 1A-1C ship

11 engine for propulsion

2 storage tank

3 transfer piping

32 heater

33 bypass line

35 dispensing mechanism

4 service storage tank

5 supply line

51 pump

6 return line

63 cooler

And 8, controlling the device.

Claims

1. A ship is characterized by comprising:

a propulsion engine using LPG as fuel;

a service tank connected to the propulsion engine through a supply line and a return line and storing LPG;

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

a pump disposed in the supply line; and

and a heater provided on the transfer line and heating 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.

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

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

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 dispensing mechanism to adjust the heating amount of the LPG in the heater.

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

the control means 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 is characterized by comprising: a propulsion engine using LPG as fuel;

a pump disposed in the supply line; and

a cooler provided in the return line and cooling 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: a control device for adjusting the cooling amount of LPG in the cooler in the form that the temperature of LPG in the service storage tank is higher than the atmospheric temperature.