KR102303751B1 - Ship - Google Patents

Abstract

A ship has a fuel tank for storing LPG, a propulsion engine using LPG as fuel, a fuel supply line for supplying LPG to the engine from the fuel tank, a pump installed in the fuel supply line, and a fuel tank from the engine. A fuel recovery line for recovering unused LPG, a pressure control valve installed in the fuel recovery line, a control device for controlling a pump and a pressure control valve, and a pressure gauge for detecting the pressure of LPG supplied to the engine, the control device includes: , the relationship between the target opening degree of the pressure regulating valve and the fuel consumption of the engine is stored in advance, and the control device controls the pressure regulating valve so that the pressure detected by the pressure gauge becomes a set value, and at the same time, the opening degree of the pressure regulating valve determines the The pump is controlled so that the target opening degree corresponds to the actual fuel consumption amount.

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, and 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, the ship which supplies LPG from a fuel tank to a propulsion engine in a liquid state is disclosed. In the case of using LPG as a fuel, there is an advantage that a measure against sulfur oxides is unnecessary compared to fuel oil, and carbon dioxide emission is small, and there is an advantage that the fuel tank can be downsized because of its large specific gravity compared to LNG.

Korean Patent Publication No. 2012-0113398

In the case of using LPG as fuel, it is considered that the fuel tank and the propulsion engine are connected by a fuel supply line and a fuel recovery line to circulate LPG between the fuel tank and the engine and use only the necessary amount in the engine.

However, in the case of circulating LPG between the fuel tank and the engine as described above, it is preferable to supply a slightly larger amount of fuel to the engine than the fuel consumption of the engine. To realize this, the flow rate of LPG supplied to the engine (the flow rate flowing into the engine through the fuel supply line) or the recovery flow rate from the engine (the flow rate flowing out of the engine through the fuel recovery line) is detected by the flowmeter, and detection It is contemplated to control the pump installed in the fuel supply line so that the obtained flow rate becomes a predetermined value corresponding to the fuel consumption of the engine.

In addition, in order to maintain the fuel supply pressure to the engine within the required range of the engine, the pressure of LPG supplied to the engine is detected with a pressure gauge, and the pressure control valve installed in the fuel recovery line is controlled so that the detected pressure becomes a set value. are considered

However, when the pump and the pressure control valve are controlled as described above, there is a risk that the flow rate control and the pressure control may interfere.

Accordingly, an object of the present invention is to provide a ship capable of stably controlling a pump installed in a fuel supply line and a pressure regulating valve installed in a fuel recovery line.

In order to solve the above problem, the inventors of the present invention, when the discharge flow rate of the pump is increased by a certain percentage than the fuel consumption of the engine, the tank return flow rate passing through the pressure control valve installed in the fuel recovery line is also the constant ratio. Therefore, it has been found that it is possible to predetermine the target opening degree of the pressure regulating valve with respect to the fuel consumption of the engine so that the discharge flow rate of the pump is higher than the fuel consumption of the engine by a certain ratio. That is, when the pressure regulating valve reaches the target opening degree, it means that the discharge flow rate of the pump increases by a certain percentage than the fuel consumption amount of the engine. The present invention has been made in this respect.

That is, the ship of the present invention includes a fuel tank for storing LPG, a propulsion engine using LPG as fuel, a fuel supply line for supplying LPG from the fuel tank to the engine, and a pump installed in the fuel supply line; , a fuel recovery line for recovering LPG that is not used as the fuel tank from the engine, a pressure control valve installed in the fuel recovery line, a control device for controlling the pump and the pressure control valve, and the engine is supplied with and a pressure gauge for detecting the pressure of LPG, wherein the relationship between the target opening degree of the pressure control valve and the fuel consumption of the engine is stored in the control device in advance, and the control device determines the pressure detected by the pressure gauge as a set value It is characterized in that while controlling the pressure regulating valve to achieve this, the pump is controlled so that the opening degree of the pressure regulating valve becomes a target opening degree corresponding to the actual fuel consumption of the engine.

According to the above configuration, since the rotation speed of the pump as well as the opening degree of the pressure regulating valve can be adjusted based on the pressure gauge, it is possible to stably control the pump and the pressure regulating valve.

The ship further includes a bypass line branched from the fuel supply line on a downstream side of the pump and connected to the fuel recovery line or the fuel tank, and a flow rate control valve installed in the bypass line, The apparatus may control the flow rate control valve so that, when the rotation speed of the pump becomes the minimum rotation speed, the opening degree of the pressure regulating valve becomes a target opening degree corresponding to the actual fuel consumption of the engine. According to this configuration, even when the rotational speed of the pump becomes the lowest rotational speed, the supply flow rate of LPG to the engine can be increased by a certain percentage than the fuel consumption amount of the engine.

The fuel tank may store LPG so that the temperature of the LPG changes according to the atmospheric temperature. According to such a configuration, it is necessary to use the fuel tank as a pressure vessel, and a means for keeping the LPG in the fuel tank at a low temperature may be required.

According to the present invention, it is possible to stably control the pump installed in the fuel supply line and the pressure control valve installed in the fuel recovery line.

1 is a schematic configuration diagram of a ship according to an embodiment of the present invention.
2 is a table showing the relationship between the fuel consumption amount of the engine and the target opening degree of the first pressure regulating valve.

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 fuel tank 2 for storing LPG. The main component of LPG may be propane (propane gas) or butane (butane gas).

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

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

According to this embodiment, a means (eg, a heat insulating material) for maintaining the LPG at a low temperature is not provided in the storage tank 21 , and the temperature of the LPG in the storage tank 21 changes according to the atmospheric temperature. On the other hand, the LPG introduced from the LPG supply source is often about -42°C when the LPG is propane gas. Therefore, in the fuel introduction line 23, the heater 24 which heats LPG to the temperature in the range from -5 degreeC to atmospheric temperature is provided, for example. However, the heater 24 is unnecessary if the temperature of the LPG delivered to the ship 1 is -5° C. or higher because a heater is installed in an LPG supply facility on land or an LPG fuel supply ship, which is an LPG supply source.

When the component of the base layer in the storage tank 21 is only vaporized PG, the pressure of the base layer in the storage tank 21 is the saturated vapor pressure of LPG. For example, when the temperature in the storage tank 21 is 25°C, the pressure (saturated vapor pressure) of the base layer in the storage tank 21 is about 0.9 MPa in terms of the gauge pressure. In the following, all indications of pressure are gauge pressure. Here, since the saturated vapor pressure of LPG is about 1.7 MPa at 50°C, the storage tank 21 is configured to withstand, for example, up to 1.8 MPa. For reference, the saturated vapor pressure of LPG is about 0.4 MPa at 0 °C.

A pump 25 is installed inside the storage tank 21 . The number of the pumps 25 may be one or plural. The upstream end of the above-described relay line 26 is connected to the pump 25 . In addition, the downstream end of the relay line 26 is opened in the service tank 22 . Then, LPG is supplied from the storage tank 21 to the service tank 22 through the relay line 26 by the pump 25 . However, the pump 25 may be provided in the middle of the relay line 26 outside the storage tank 21 .

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

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

The service tank 22 is connected to the propulsion engine 11 by a fuel supply line 31 and a fuel recovery line 41 . That is, LPG is supplied to the engine 11 from the service tank 22 through the fuel supply line 31 , and unused LPG is recovered from the engine 11 to the service tank 22 through the fuel recovery line 41 . do. In other words, the LPG is circulated between the service tank 22 and the engine 11 through the fuel supply line 31 and the fuel recovery line 41 .

The upstream end of the fuel supply line 31 is connected to the lower portion of the service tank 22 . The downstream end of the fuel recovery line 41 is opened in the service tank 22 .

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 fuel supply line 31 and the upstream end of the fuel recovery line 41, and a plurality of fuel injection valves connected in parallel to the main flow path. do.

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

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

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

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

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

Pump 32, shut-off valves 34, 43 as described above. The pressure regulating valves 42 , 45 and the flow control valves 52 , 54 are controlled by the control device 6 . However, only some signal lines are depicted in FIG. 1 for the sake of simplification of the drawing. The control device 6 is, for example, a computer including a memory such as ROM or RAM and a CPU, and a program stored in the ROM is executed by the CPU. The control device 6 may be a single device or may be divided into a plurality of devices (eg, an engine control device and a fuel supply control device).

Regarding the shut-off valves 34 and 43 , the control device 6 closes the shut-off valves 34 and 43 while the engine 11 is stopped, and the shut-off valve 34 during standby operation and operation of the engine 11 . , 43) is opened. During the stop of the engine 11 , the flow path between the shutoff valves 34 and 43 (the downstream part of the fuel supply line 31 , the main flow path of the engine 11 and the upstream part of the fuel recovery line 41 ) is closed. It is purged with an inert gas.

The control device 6 is electrically connected to the first pressure gauge 71 (corresponding to the pressure gauge of the present invention) and the second pressure gauge 72 . The first pressure gauge 71 is used to control the pump 32 , the flow control valves 52 , 54 , and the first pressure control valve 42 , and the second pressure gauge 72 is the second pressure control valve 45 . used for control. Hereinafter, for convenience of description, control based on the second pressure regulating valve 45 will be described.

The second pressure gauge 72 is installed in the fuel recovery line 41 between the first pressure control valve 42 and the second pressure control valve 45 , and after the pressure is reduced in the first pressure control valve 42 , Detects LPG pressure. According to this embodiment, the second pressure gauge 72 is located between the shut-off valve 43 and the cooler 44 , but may be positioned on the upstream side of the shut-off valve 43 or on the downstream side of the cooler 44 .

The temperature of LPG is slightly increased as the LPG passes through the engine 11 (eg, 55°C). Accordingly, in order to prevent the LPG depressurized in the first pressure regulating valve 42 from vaporizing, the control device 6 determines that the pressure detected by the second pressure gauge 72 is higher than the saturated vapor pressure at the expected maximum temperature. The 2nd pressure regulating valve 45 is controlled so that it may become a set value (for example, 2.0 MPa).

The first pressure gauge 71 is installed in the fuel supply line 31 on the downstream side of the pump 32 , and detects the pressure of LPG supplied to the engine 11 . According to this embodiment, the first pressure gauge 71 is located on the downstream side of the shut-off valve 34 , but it may be positioned between the shut-off valve 34 and the heater 33 or on the upstream side of the heater 33 . .

The control device 6 sets the pressure detected by the first pressure gauge 71 to a set value within the required range of the engine 11 (eg, 5.0 to 6.0 MPa when the engine 11 is a diesel cycle). 1 Control the pressure regulating valve (42).

As for the pump 32 and the flow control valve 52 , in the control device 6 , the relationship between the target opening degree of the first pressure control valve 42 and the fuel consumption Qe of the engine 11 is shown in FIG. 2 . It is stored in advance as a table as shown. The target opening degree of the first pressure regulating valve 42 generally increases as the fuel consumption Qe of the engine 11 increases.

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

And the control apparatus 6 controls the pump 32 so that the opening degree of the 1st pressure regulating valve 42 may become a target opening degree corresponding to the actual fuel consumption Qe of the engine 11. As shown in FIG. That is, when the actual opening degree of the first pressure control valve 42 is smaller than the target opening degree, the rotation speed of the pump 32 is increased to increase the fuel supply pressure to increase the opening degree of the first pressure control valve 42 . do. Conversely, when the actual opening degree of the first pressure control valve 42 is larger than the target opening degree, the rotation speed of the pump 32 is reduced in order to reduce the opening degree of the first pressure control valve 42 by lowering the fuel supply pressure.

For example, when the load on the engine 11 increases and the fuel consumption Qe of the engine 11 increases, since the target opening degree of the first pressure regulating valve 42 rises, the control device 6 The rotation speed of the pump 32 is increased to raise the actual opening degree of the first pressure regulating valve 42 to the target opening degree. Conversely, when the load on the engine 11 decreases and the fuel consumption Qe of the engine 11 decreases, the target opening degree of the first pressure regulating valve 42 decreases, so that the control device 6 controls the first pressure The rotation speed of the pump 32 is reduced to reduce the actual opening degree of the regulating valve 42 to the target opening degree.

Here, the control device 6 keeps the flow rate control valve 52 fully closed as long as the rotation speed of the pump 32 does not become the minimum rotation speed. Although the minimum rotation speed of the pump 32 may be a fixed value, for example, it changes corresponding to the pressure of the base layer in the service tank 22 (the higher the pressure of the base layer in the service tank 22, the higher the speed of the pump 32) It is preferable to make the minimum rotation speed low).

As a result of the control based on the target opening degree of the first pressure regulating valve 42 , when the rotation speed of the pump 32 becomes the lowest rotation speed, the control device 6 determines that the opening degree of the first pressure control valve 42 is the engine ( Either one of the flow control valves 52 and 54 is controlled so as to become a target opening degree corresponding to the actual fuel consumption Qe of 11). That is, when the actual opening degree of the first pressure control valve 42 is smaller than the target opening degree, any one of the flow control valves 52 and 54 increases the fuel supply pressure to increase the opening degree of the first pressure control valve 42 . The opening on one side is reduced. Conversely, when the actual opening degree of the first pressure regulating valve 42 is larger than the target opening degree, any of the flow control valves 52 and 54 is used to lower the fuel supply pressure to decrease the opening degree of the first pressure regulating valve 42 . The opening on one side is increased.

As described above, in the ship 1 according to the present embodiment, not only the opening degree of the first pressure control valve 42 but also the rotation speed of the pump 32 can be adjusted based on the first pressure gauge 71 . , the pump 32 and the first pressure control valve 42 can be stably controlled.

(variant example)

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.

For example, when both the first bypass line 51 and the second bypass line 53 are omitted and the rotation speed of the pump 32 becomes the lowest rotation speed, a large amount of LPG passes through the engine 11 . may be allowed However, when at least one of the first bypass line 51 and the second bypass line 53 is formed, and the rotation speed of the pump 32 becomes the lowest rotation speed, the first bypass line 51 or the second bypass line 2 When the flow control valve 52 or 54 installed in the bypass line 53 is opened, even when the rotation speed of the pump 32 becomes the lowest rotation speed, the supply flow rate of LPG to the engine 11 is controlled by the engine 11 . It can be made higher than the fuel consumption (Qe) by a certain percentage.

Alternatively, when the second bypass line 53 is provided, the LPG passing through the engine 11 may temporarily increase when the rotation speed of the pump 32 becomes the minimum rotation speed. The LPG returned to the service tank 22 through the second bypass line 53 is heated by the pump 32 . Accordingly, as described above, when the LPG passing through the engine 11 temporarily increases when the rotation speed of the pump 32 reaches the lowest rotation speed, the flow to the service tank 22 through the second bypass line 53 is While the conveyance amount decreases, since the LPG passing through the engine 11 is cooled by the cooler 44 , the temperature rise of the LPG in the service tank 22 can be suppressed. Specifically, when the rotation speed of the pump 32 becomes the minimum rotation speed, the control device 6 increases the target opening degree of the first pressure regulating valve 42 . As such, the target opening degree of the first pressure regulating valve 42 does not always need to be increased as the fuel consumption Qe of the engine 11 increases as shown in FIG. 2 .

In addition, in the above embodiment, although the fuel tank 2 was constituted by the storage tank 21 and the service tank 22 , the storage tank 21 is omitted, and the fuel tank 2 is only the service tank 22 . may be configured. That is, LPG may be directly introduced into the service tank 22 from the LPG supply source. However, if the configuration is the same as in the above embodiment, the fuel tank 2 can be divided into a storage tank 21 for introducing LPG and a service tank 22 for circulating LPG.

In addition, the fuel tank 2 does not necessarily need to be a pressure vessel, and may be a tank whose internal pressure is about the same as atmospheric pressure. In this case, a means for maintaining the LPG in the fuel tank 2 at a low temperature is required. However, if the fuel tank 2 stores LPG so that the temperature of the LPG changes according to the atmospheric temperature as in the above embodiment, it is necessary to use the fuel tank 2 as a pressure vessel. may require a means for maintaining the low temperature.

1: ship
11: engine
2: fuel tank
31: fuel supply line
32: pump
41: fuel recovery line
43, 45: pressure regulating valve
51: bypass line
52: flow control valve
6: control unit
71 to 73: pressure gauge

Claims (3)

a fuel tank for storing LPG;
An engine for propulsion using LPG as fuel;
a fuel supply line for supplying LPG from the fuel tank to the engine;
a pump installed in the fuel supply line;
a fuel recovery line for recovering LPG that is not used as the fuel tank from the engine;
a pressure regulating valve installed in the fuel recovery line;
a control device for controlling the pump and the pressure regulating valve;
and a pressure gauge for detecting the pressure of LPG supplied to the engine,
a relationship between the target opening degree of the pressure regulating valve and the fuel consumption of the engine is stored in the control device in advance;
The control device controls the pump so that the opening degree of the pressure regulating valve becomes a target opening degree corresponding to the actual fuel consumption of the engine while controlling the pressure regulating valve so that the pressure detected by the pressure gauge becomes a set value. Characterized ship.
According to claim 1,
a bypass line branching from the fuel supply line on the downstream side of the pump and connected to the fuel recovery line or the fuel tank;
Further comprising a flow control valve installed in the bypass line,
Said control device controls said flow control valve so that the opening degree of the said pressure regulating valve may become a target opening degree corresponding to the actual fuel consumption of the said engine when the rotation speed of the said pump becomes a minimum rotation speed, The ship characterized by the above-mentioned. .
3. The method of claim 1 or 2,
The fuel tank is a vessel, characterized in that for storing the LPG so that the temperature of the LPG changes according to the atmospheric temperature.

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