KR102404713B1 - Ship - Google Patents

Abstract

The ship has a propulsion engine using LPG as fuel, a service tank that is connected to the propulsion engine by a supply line and a conveyance line, and stores LPG, and a service tank through a transfer line, and is more than the LPG in the service tank. A storage tank for storing low-temperature LPG, a pump installed on the supply line, and a heater installed on the transfer line to heat the LPG supplied from the storage tank to the service tank so that the temperature of the LPG in the service tank becomes higher than the ambient temperature. be prepared

Description

Ship

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

In conventional ships, generally, the fuel of a propulsion engine was fuel oil, such as heavy oil, or LNG (Liquefied Natural Gas). In recent years, it has also been proposed to use LPG (Liquefied Petroleum Gas) as a fuel for a propulsion engine.

For example, in patent document 1, the ship which supplies LPG in a liquid state from a fuel tank to the engine for propulsion is disclosed. When LPG is used as a fuel, there is an advantage that a measure against sulfur oxides is unnecessary compared to fuel oil, and carbon dioxide emission is reduced, and there is a merit that the fuel tank can be downsized because of its high specific gravity compared to LNG.

Korean Patent Publication No. 2012-0113398

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

In the case of circulating LPG as described above, it is heated when the LPG passes through the engine. Therefore, it is preferable to divide the fuel tank into a service tank for LPG circulation and a storage tank for maintaining the LPG. 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 capable of withstanding high pressure, and even if the temperature of the LPG in the service tank becomes above atmospheric temperature, the equilibrium state of the LPG is maintained by the high pressure in the service tank.

The temperature of the LPG in the storage tank may be equal to or less than the saturation temperature at atmospheric pressure, but similarly to the service tank, the storage tank may be a pressure vessel, and the equilibrium state of the LPG may be maintained by the high pressure in the storage tank. From the storage tank to the service tank, through a transfer line connecting them, LPG in an amount corresponding to the fuel consumption of the engine is supplied.

A pump is installed in the above-mentioned supply line. If 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 receiving heat from the atmosphere while flowing the supply line from the service tank to the pump. In this case, damage or performance degradation of the pump occurs. For example, when LPG having a temperature lower than the ambient 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 ambient temperature.

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

In order to solve the above problems, a ship according to an aspect of the present invention includes a propulsion engine using LPG as fuel, a service tank connected to the propulsion engine by a supply line and a return line, and storing LPG, A storage tank connected to the service tank by a transfer line and storing LPG at a lower temperature than the LPG in the service tank, a pump installed in the supply line, and a pump installed in the transfer line, from the storage tank to the service tank It is characterized in that it includes a heater for heating the LPG supplied 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 suppressed that the temperature of the LPG in the service tank becomes lower than the atmospheric temperature due to insufficient heating amount of the LPG in the heater. Accordingly, it is possible to prevent vaporization of LPG at the inlet of the pump.

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

For example, the vessel may include a bypass line branching from the transfer line on an upstream side of the heater and joining the transfer line on a downstream side of the heater, and a flow rate of LPG passing through the heater and the bypass A distribution mechanism for changing the ratio of the LPG flow rate flowing through the line may be further provided, wherein the control device controls the distribution mechanism to adjust the heating amount of LPG in the heater.

The ship is installed in the conveyance line, further comprising a cooler for cooling the LPG conveyed from the propulsion engine to the service tank, the control device so that the temperature of the LPG in the service tank is higher than the atmospheric temperature, You may adjust not only the heating amount of LPG in the heater, but also the amount of LPG cooling in the cooler. According to this structure, since the LPG conveyed from the engine to the service tank is cooled by the cooler, it is possible to suppress an excessive increase in the temperature of the LPG in the service tank. Furthermore, by adjusting the cooling amount of LPG in addition to the heating amount of LPG, it is possible to respond to various situations.

In addition, a ship according to another aspect of the present invention includes a propulsion engine using LPG as a fuel, a service tank connected to the propulsion engine by a supply line and a conveyance line, and storing LPG, and a transfer line. A storage tank connected to the service tank and storing LPG at a lower temperature than the LPG in the service tank, a pump installed in the supply line, and LPG installed in the return line and returned from the propulsion engine to the service tank It is characterized in that it is provided with a cooler for cooling the temperature of the LPG in the service tank to be higher than the atmospheric temperature.

According to the above configuration, since the LPG conveyed from the engine to the service tank is cooled by the cooler, it is possible to suppress an excessive increase in the temperature of the LPG in the service tank. Moreover, according to the said structure, it is suppressed that the cooling amount of LPG in a cooler becomes excessive and the temperature of LPG in a service tank becomes lower than atmospheric temperature. Accordingly, it is possible to prevent vaporization of LPG at the inlet of the pump.

For example, the ship may further include a control device that adjusts the cooling amount of the LPG in the cooler so that the temperature of the LPG in the service tank becomes higher than the atmospheric temperature.

According to the present invention, it is possible to prevent the vaporization of LPG at the inlet of the pump installed in the supply line.

1 is a schematic configuration diagram of a ship according to an embodiment of the present invention.
[ Fig. 2 ] It is a schematic configuration diagram of a ship of a modified example.
[FIG. 3] A schematic configuration diagram of a ship according to the first alternative means.
Fig. 4 is an enlarged view of the service tank in the first alternative means.
[FIG. 5] It is a cross-sectional view taken along the line VV of FIG.
Fig. 6 is an enlarged view of the service tank in the second alternative means.
[Fig. 7] A schematic configuration diagram of a ship according to the third alternative means.
[Fig. 8] It is a schematic configuration diagram of a ship according to the fourth alternative means.
[FIG. 9] An enlarged view of the service tank in the fourth alternative means.
[Fig. 10] It is an enlarged view of the service tank of the modification of the 4th replacement means.

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

The engine 11 is connected to the service tank 4 by a supply line 5 and a conveyance 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 by a transfer line 3 . For example, the volume of the storage tank 2 is greater than the volume of the service tank 4 .

The engine 11 is, for example, a reciprocating engine of a diesel cycle or an auto cycle. Although not shown, the engine 11 includes a main flow path 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 to each other in parallel to the main flow path. The fuel injection valve injects LPG into the air supplied into the cylinder in a liquid state. However, the engine 11 may be a gas turbine engine.

The supply line 5 is provided with a pump 51 , a heater 52 , and a shutoff valve 53 in order from the upstream side. The number of the pumps 51 may be one or plural. The heater 52 heats the LPG supplied to the engine 11 from the service tank 4 to a required temperature of the engine 11 (eg, up to 45° C.). The upstream end of the supply line 5 is connected to the lower end of the service tank 4 . For example, the heater 52 is a heat exchanger that performs heat exchange between the heating medium fluid and LPG.

The transfer 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 order from the upstream side. The positions of the shutoff valve 61 and the first pressure regulating valve 62 may be opposite to each other. The cooler 63 cools the LPG returned from the engine 11 to the service tank 4 (LPG heated by passing through the engine 11) to a predetermined temperature (eg, 40°C). Here, the cooler 63 may be omitted. The conveying line 6 extends to the inside of the service tank 4 . For example, the cooler 63 is a heat exchanger that performs heat exchange between the heating medium fluid and LPG.

In this embodiment, the supply line 5 and the conveyance line 6 are connected by a bypass line 71 . A bypass line 71 branches from the supply line 5 between the heater 52 and the shut-off valve 53 , and a return line 6 between the first pressure regulating valve 62 and the cooler 63 . is joining the The bypass line 71 is provided with a shut-off valve 72 . However, instead of the shutoff valve 72 , a flow control valve may be provided in the bypass line 71 .

The service tank 4 is a pressure vessel capable of withstanding 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 depends on the ambient temperature, the temperature of the LPG supplied from the storage tank 2 , the temperature of the LPG conveyed from the engine 11 , etc. change That is, the equilibrium state of LPG is maintained by the high pressure in the service tank 4 . For example, assuming that the temperature of LPG in the service tank 4 is 0 to 50° C., the pressure (saturated vapor pressure) of the base layer in the service tank 4 is about 0.4 MPa to about 1.8 MPa as a gauge pressure. to be. In the following, all indications of pressure are gauge pressure. However, the service tank 4 may be covered with a heat 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. This low temperature may be lower than the saturation temperature at atmospheric pressure (in propane gas, -42° C.) or higher than the saturation temperature at atmospheric pressure, as long as it is lower than the temperature (more preferably atmospheric temperature) of the LPG in the service tank 4 . . However, the storage tank 2 is a pressure vessel similar to the service tank 4 , and the equilibrium state of LPG may be maintained by the high pressure in the storage tank 2 .

In the storage tank 2 , a pump 21 is disposed. The number of the pumps 21 may be one or plural. The upstream end of the transfer line 3 described above is connected to the pump 21 . The transfer line 3 extends to the inside of the service tank 4 . However, the pump 21 may be installed outside the storage tank 2 in the middle of the transfer line 3 .

From the storage tank 2 to the service tank 4 , LPG in an amount corresponding to the fuel consumption of the engine 11 is supplied through a transfer line 3 . Such supply of LPG may be performed continuously or may be performed intermittently. The transfer line 3 is provided with a heater 32 that heats the LPG supplied from the storage tank 2 to the service tank 4 to a predetermined temperature (eg, 0 to 45° C.). For example, the heater 32 is a heat exchanger that performs heat exchange between the heating medium fluid and LPG.

In the present embodiment, a bypass line 33 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 joins the transfer line 3 on the downstream side of the heater 32 .

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

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

The above-described pump 51 and various valves are controlled by a control device 8 . However, in FIG. 1, only some signal lines are depicted for the sake of simplification of the drawing. The control device 8 is, for example, a computer provided with a CPU and a memory such as a ROM or RAM, and the 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 (eg, an engine control device and a fuel supply control device).

As for the shutoff valves 53 and 61 , the control device 8 closes the shutoff valves 53 and 61 while the engine 11 is stopped, and opens the shutoff valves 53 and 61 while the engine 11 is running. . During the stop of the engine 11 , the flow path between the shut-off valves 53 and 61 (the downstream part of the supply line 5 , the main flow path of the engine 11 and the upstream part of the return line 6 ) is closed with inert gas. is purged with

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 amount of the engine 11 . For example, when the load of the engine 11 is high, the surplus flow rate, which is the flow rate of LPG flowing from the engine 11 into the conveyance line 6, is detected by a flow meter (not shown), and this surplus flow rate is measured by the engine ( The pump 51 is controlled so as to be a constant ratio to the fuel consumption of 11). Instead of the surplus flow rate, a supply flow rate that is a flow rate of LPG flowing from the supply line 5 to 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.

As for the shutoff valve 72 , the control device 8 opens the shutoff valve 72 and closes the shutoff valve 53 before starting the engine 11 until the flow rate of the pump 51 is stabilized. 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 . During the operation of the engine 11 , when the engine supply pressure (pressure detected by the first pressure gauge 91 to be described later) rises due to a sudden decrease in the load on the engine 11 or the like, the control device 8 shuts off The valve 72 is opened to suppress an increase in 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 installed in the supply line 5 on the downstream side from the branch point of the bypass line 71 , and detects the pressure of LPG supplied to the engine 11 . The second pressure gauge 92 is installed in the return line 6 between the first pressure control valve 62 and the second pressure control valve 64 , and detect the pressure.

The control device 8 is configured such that the pressure detected by the first pressure gauge 91 becomes the required pressure of the engine 11 (eg, 5 to 6 MPa when the engine 11 is a reciprocating engine of a diesel cycle). The first pressure regulating valve 62 is controlled.

As described above, since LPG is heated by passing through the engine 11, the temperature of the LPG flowing from the engine 11 to the return line 6 is slightly higher (for example, 55°C). Accordingly, in order to prevent the LPG decompressed by the first pressure regulating valve 62 from being vaporized, the control device 8 determines that the pressure detected by the second pressure gauge 92 is higher than the saturated vapor pressure at the assumed maximum temperature. The second pressure regulating valve 64 is controlled to a set value (eg, 3.5 MPa).

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

Then, the control device 8 controls the first flow control valve 31 so that the temperature of the LPG in the service tank 4 detected by the second thermometer 82 becomes higher than the atmospheric temperature detected by the first thermometer 81 . and the second flow control valve 34 (dispensing mechanism 35 ) to adjust the heating amount of LPG in the heater 32 . Here, 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 ship 1 of this embodiment, since the heating amount of LPG in the heater 32 is appropriately adjusted, the heating amount of LPG in the heater 32 is insufficient, so that the LPG in the service tank 4 The temperature is suppressed from being lower than the ambient temperature. Accordingly, vaporization of LPG at the inlet of the pump 51 can be prevented.

In addition, in this embodiment, since the LPG conveyed 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.

<Modified example>

The present invention is not limited to the above-described embodiment, and various modifications are possible 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 , the second thermometer 83 provided in the transfer line 3 may be employed. The second thermometer 83 detects the transfer temperature, which is the temperature of the LPG after the LPG passing through the heater 32 and the LPG flowing through the bypass line 33 are mixed.

In this case, the control device 8 first controls a conveyance flow rate that is the flow rate of LPG flowing from the conveyance line 6 to the service tank 4 , a conveyance flow rate that is a flow rate of LPG flowing from the conveyance line 3 to the service tank 4 , and from the ambient temperature, a target transfer temperature required for the temperature of the LPG in the service tank 4 to become higher than the ambient temperature is calculated. And the control device 8 sets the 1st flow control valve 31 and the 2nd flow control valve 34 (distribution mechanism 35) so that the conveyance temperature detected by the 2nd thermometer 83 may become a target conveyance temperature. to control

In addition, when the heater 32 is a heat exchanger performing heat exchange between the heating medium fluid and LPG, and the temperature of the heating medium fluid supplied to the heater 32 can be changed, the bypass line 33 and the flow rate control valve 31 , 34) may be omitted, and the heating amount of LPG in the heater 32 may be adjusted by changing the temperature of the heating medium fluid supplied to the heater 32 by the controller 8 .

In addition, the control device 8 may adjust not only the heating amount of LPG in the heater 32 but also the cooling amount of 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 cooling amount of the LPG in addition to the heating amount of the LPG, it is possible to respond to various situations.

When adjusting the cooling amount of LPG in the cooler 63, although not shown, a bypass line is connected to the return line 6 to bypass the cooler 63, and the LPG passing through the cooler 63 is The cooling amount of LPG in the cooler 63 may be adjusted by changing the ratio of the flow rate and the flow rate of the LPG flowing through the bypass line. Alternatively, when the cooler 63 is a heat exchanger that performs heat exchange between the heating medium fluid and LPG, and the temperature of the heating medium fluid supplied to the cooler 63 is changeable, the temperature of the heating medium fluid supplied to the cooler 63 is You may adjust the cooling amount of LPG in the cooler 63 by changing it.

When adjusting not only the heating amount of LPG in the heater 32 but also the cooling amount of LPG in the cooler 63, for example, the amount of LPG in the heater 32 is adjusted compared to the case where only the heater 32 is adjusted. While reducing the heating amount, the cooling amount of LPG in the cooler 63 may be decreased.

In addition, the control device 8 adjusts only the cooling amount of LPG in the cooler 63 without adjusting the heating amount of LPG in the heater 32 so that the temperature of the LPG in the service tank 4 becomes higher than the atmospheric temperature. you can do it According to this structure, it is suppressed that the cooling amount of LPG in the cooler 63 becomes excessive and the temperature of LPG in the service tank 4 becomes lower than atmospheric temperature. Accordingly, vaporization of LPG at the inlet of the pump 51 can be prevented. Naturally, in the case of adjusting only the cooling amount of LPG in the cooler 63, the heater 32 can be omitted.

1 and 2, the shape of the service tank 4 is a vertically long cylindrical shape, but the service tank 4 may have other shapes such as a horizontally long cylindrical shape, a spherical shape, a cube shape, and a rectangular parallelepiped shape. . Similarly, the shape of the storage tank 2 can also be arbitrarily changed. This is also the case for alternative means, which will be described later.

(alternative means)

In the above-described embodiment, in order to prevent vaporization of LPG at the inlet of the pump 51, a means for making the temperature of the LPG in the service tank 4 higher than the atmospheric temperature is employed. However, in order to prevent vaporization of LPG at the inlet of the pump 51, it is also possible to employ other means.

In the service tank 4 , the relatively low temperature LPG (supply LPG) supplied through the conveying line 3 and the relatively high temperature LPG (conveying LPG) conveyed through the conveying line 6 are mixed. However, before the supply LPG and the return LPG are completely mixed, if the return LPG at a relatively high temperature flows out from the service tank 4 through the supply line 5 , at the inlet of the pump 51 installed in the supply line 5 . LPG can vaporize. In this case, damage to the pump 51 or performance degradation occurs.

Accordingly, in view of the above, first to fourth alternative means are considered as described below. Here, in the first to fourth alternative means, the same reference numerals are assigned to the same components as in the above embodiment, and the overlapping description is omitted.

(first alternative means)

3 shows a vessel 1A according to a first alternative means. This vessel 1A differs from the vessel 1 shown in FIG. 1 in that it does not include a bypass line 33 , a first flow control valve 31 and a second flow control valve 34 . However, similarly to the above-described embodiment, the vessel 1A includes a bypass line 33 , a first flow control valve 31 , and a second flow control valve 34 , and the first flow control valve 31 . and the second flow control valve 34 may be controlled similarly to the above embodiment. In addition, in the first alternative means, special measures are taken for the service tank 4 .

The service tank 4 will be described in more detail with reference to FIGS. 4 and 5 , a downstream part extending from the outside to the inside of the service tank 4 in the conveying line 6 and the service tank in the conveying line 3 . The downstream portion extending from the outside to the inside of (4) is configured such that the LPG flowing out from the downstream end of the conveying line 6 and the downstream end of the conveying line 3 forms a swirl flow.

In the first alternative means, in the service tank 4 (precisely, in the liquid layer 40 made of LPG), a bowl-shaped (inverted cone-shaped) guide member 45 that has a diameter reduced downwardly is disposed. has been The downstream end of the conveying line 6 and the downstream end of the conveying line 3 are located above the guide member 45 , and the upstream end of the supply line 5 is below the guide member 45 and the service tank 4 is connected to

The downstream part of the conveying line 6 is slightly with respect to the horizontal direction which is the circumferential direction of the guide member 45 so that LPG flowing out from the downstream end of the conveying line 6 obliquely collides with the upper surface of the guide member 45 . bent downwards. Similarly, the downstream portion of the transfer line 3 is in the horizontal direction, which is the circumferential direction of the guide member 45, so that LPG flowing out from the downstream end of the transfer line 3 obliquely collides with the upper surface of the guide member 45. It is slightly bent downwards. Accordingly, the LPG flowing out from the downstream end of the conveying line 6 and the downstream end of the conveying line 3 forms a swirling flow along the upper surface of the guide member 45 .

In the vessel 1A having the configuration as described above, a relatively high temperature conveying LPG (LPG conveyed to the service tank 4 through the conveying line 6) and a relatively low temperature supply LPG (transfer line 3) LPG) supplied to the service tank 4 through the vortex flow is mixed. Accordingly, the temperature of the LPG in the service tank 4 becomes uniform, and vaporization of the LPG at the inlet of the pump 51 can be prevented.

<Modified example>

In the first alternative means, a guide member 45 is arranged in the service tank 4 , but the downstream part of the conveying line 6 and the downstream side of the conveying line 3 are positioned in the circumferential direction of the guide member 45 . In the case of bending in the horizontal direction, the guide member 45 may be omitted. However, if the guide member 45 is provided as in the first alternative means, it is possible to reliably form a swirling flow above the guide member 45 .

(Second alternative means)

Next, a ship according to the second alternative means will be described with reference to FIG. 6 . The only difference between the ship of the second alternative means and the ship 1A of the first alternative means is the structure in the service tank 4 .

Specifically, in the second alternative means, the downstream end of the conveying line 6 is located in the service tank 4 below the downstream end of the conveying line 3 .

In addition, in the second alternative means, a partition member 46 is arranged in the service tank 4 . The partition member 46 partitions the liquid layer 40 made of LPG (the base layer is made of PG in which LPG is vaporized) into a first region 41 and a second region 42 . The upstream end of the supply line 5 communicates with the first area 41 , and the downstream end of the conveying line 6 and the downstream end of the conveying line 3 are located in the second area 42 .

In the second alternative means, 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 a horizontal direction. However, the partition member 46 is a plate parallel to the horizontal direction, and the first region 41 may be positioned below the second region 42 . In this case, the partition member 46 may be a perforated plate made of a mesh material or punched metal. Alternatively, the partition member 46 is a cylinder extending in the vertical direction such that the first area 41 is located in the center of the service tank 4 and the second area 42 is located around the first area 41 . Any shape is fine.

In the same configuration as the second alternative means, the conveyed LPG rises in the service tank 4 as shown by the arrow in FIG. 6 due to the difference in density between the relatively high temperature conveyed LPG and the relatively low temperature supply LPG, Supply LPG goes down. Accordingly, the return LPG and the supply LPG are mixed by convection. Accordingly, the temperature of the LPG in the service tank 4 becomes uniform, and vaporization of the LPG at the inlet of the pump 51 can be prevented.

<Modified example>

Even without the partition member 46, since conveyed LPG and supplied LPG are mixed by convection, the partition member 46 may be omitted. However, if the partition member 46 is provided, the conveyed LPG and the supplied LPG can be sufficiently mixed in the second region 42 .

(third alternative means)

7 shows a vessel 1B according to a third alternative means. In a third alternative means, the conveying line 6 and the conveying line 3 are joining each other outside the service tank 4 . Accordingly, the downstream side portion of the conveying line 6 and the downstream side portion of the conveying line 3 become a common flow path extending from the outside to the inside of the service tank 4 .

More specifically, the conveying line 6 joins the conveying line 3 on the downstream side of the second pressure regulating valve 64 . The conveying line 6 is provided with a check valve 65 between the junction of the second pressure regulating valve 64 and the conveying line 3 .

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

As for the merging form of the conveyance line 6 and the conveyance line 3, the thing in which three pipes were connected in a T-shape or a Y-shape may be sufficient. Alternatively, a container is provided at the junction of the transfer line 6 and the transfer line, and three pipes may be connected to the container.

In the vessel 1B having the configuration as described above, after the conveyance LPG at a relatively high temperature and the supply LPG at a relatively low temperature are mixed with each other, they are then introduced into the service tank 4 . Accordingly, the temperature of the LPG in the service tank 4 becomes uniform, and vaporization of the LPG at the inlet of the pump 51 can be prevented.

(4th alternative means)

8 shows a vessel 1C according to a fourth alternative means. This vessel 1C includes a bypass line 33 , a first flow rate control valve 31 , and a second flow rate control valve 34 , similarly to the above-described embodiment. As described in the above embodiment, the first flow control valve 31 and the second flow control valve 34 have the ratio of the flow rate of LPG passing through the heater 32 to the flow rate of LPG flowing through the bypass line 33 . constitute a dispensing mechanism 35 to change .

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

In the fourth alternative means, special measures are taken for the service 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 transfer line 6 in the service tank 4 . Further, 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 means, a partition member 47 is arranged in the service tank 4 . The partition member 47 partitions the liquid layer 40 made of LPG (the base layer is made of PG in which LPG is vaporized) into the first region 41 and the second region 42 . The upstream end of the supply line 5 communicates with the first area 41 , the downstream end of the transfer line 3 is located in the first area 41 , and the downstream end of the conveying line 6 communicates with the second area (42) is located within.

In the fourth alternative means, the partition member 47 is a horizontal perforated plate, the first region 41 is a region below the partition member 47 , and the second region 42 is an upper region of the partition member 47 . to be. As such a perforated plate, a mesh material, punching metal, etc. are used, for example.

The control device 8 is also electrically connected to the first thermometer 84 and the second thermometer 85 . The first thermometer 84 is installed in the service tank 4 , and detects the temperature of the upper portion of the liquid layer 40 in the service tank 4 (in this embodiment, the second region 42 ). The temperature of the upper part of the liquid layer 40 is influenced by the temperature distribution (density distribution) in the service tank 4 , and is equal to or less than the temperature of the liquid level in the service tank 4 . The second thermometer 85 is installed in the transfer line 3 on the downstream side of the junction of the bypass line 33 and passes through the LPG (heater 32) flowing from the transfer line 3 to the service tank 4 . The temperature of LPG after mixing of one LPG and LPG flowing through the bypass line 33 is detected.

Then, the control device 8 maintains the temperature of the LPG detected by the second thermometer 85 to be lower than the temperature of the LPG detected by the first thermometer 84 (the temperature below the liquid level in the service tank 4). As much as possible, the heating amount of LPG in the heater 32 is adjusted by controlling the first flow control valve 31 and the second flow control valve 34 (distribution mechanism 35 ).

As described above, in the ship 1C of the fourth alternative means, since the downstream end of the conveying line 3 is located below the downstream end of the conveying line 6 in the service tank 4, conveying LPG Supply line 5 is preferentially supplied by cold supply LPG (LPG supplied to service tank 4 via transfer line 3) rather than (LPG returned to service tank 4 via transfer line 6). through the service tank (4). Thereby, vaporization of LPG at the inlet of the pump 51 can be prevented.

Furthermore, in the fourth alternative means, since the heater 32 is installed in the transfer line 3, even if the temperature of the LPG in the storage tank 2 is below the saturation temperature at atmospheric pressure, the supplied LPG can be heated by the heater. can Accordingly, the service tank 4 can be made of general steel instead of special steel for low temperature (eg, steel having toughness even at -46°C or lower). In addition, since the heating amount of the supply LPG is adjusted so that the temperature of the LPG flowing from the transfer line 3 to the service tank 4 is kept lower than the temperature of the upper part of the liquid layer 40 in the service tank 4, the heater 32 ), the effect of preferentially flowing out of the low-temperature supply LPG described above can be reliably obtained.

<Modified example>

The partition member 47 does not necessarily have to be a horizontal perforated plate, and may have an inverted L-shaped cross-section as shown in FIG. 10, or may have other shapes. Alternatively, the partition member 47 itself may be omitted.

However, as shown in FIGS. 9 and 10 , when the partition member 47 is disposed in the service tank 4 , the effect that the supply LPG preferentially flows out through the supply line can be remarkably obtained.

1, 1A to 1C: Ship
11: propulsion engine
2: storage tank
3: transfer line
32: burner
33: bypass line
35: dispensing mechanism
4: service tank
5: supply line
51: pump
6: conveying line
63: cooler
8: control unit

Claims (6)

An engine for propulsion using LPG as fuel;
a service tank connected to the propulsion engine by a supply line and a return line and storing LPG;
a storage tank connected to the service tank by a transfer line and storing LPG at a lower temperature than the LPG in the service tank;
a pump installed in the supply line;
and a heater installed 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. The method of claim 1,
The vessel, characterized in that it further comprises 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 method of claim 2,
a bypass line branching from the transfer line on an upstream side of the heater and joining the transfer line on a downstream side of the heater;
Further comprising a distribution mechanism for changing the ratio of the flow rate of LPG passing through the heater and the LPG flow rate flowing through the bypass line,
The control device controls the distribution mechanism to adjust the heating amount of LPG in the heater. 4. The method of claim 2 or 3,
Installed in the conveying line, further comprising a cooler for cooling the LPG conveyed from the propulsion engine to the service tank,
The control device is a vessel, characterized in that for controlling the amount of LPG cooling in the cooler as well as the heating amount of the LPG in the heater so that the temperature of the LPG in the service tank becomes higher than the atmospheric temperature. An engine for propulsion using LPG as fuel;
a service tank connected to the propulsion engine by a supply line and a return line and storing LPG;
a storage tank connected to the service tank by a transfer line and storing LPG at a lower temperature than the LPG in the service tank;
a pump installed in the supply line;
and a cooler installed in the conveying line and cooling the LPG conveyed from the propulsion engine to the service tank so that the temperature of the LPG in the service tank becomes higher than atmospheric temperature. 6. The method of claim 5,
The vessel, characterized in that it further comprises a control device for adjusting the cooling amount of the LPG in the cooler so that the temperature of the LPG in the service tank is higher than the atmospheric temperature.

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