JP6757217B2 - Ship - Google Patents

Description

The present invention relates to a ship including a main gas engine for propulsion and a sub gas engine for an inboard power source.

Conventionally, a ship including a main gas engine for propulsion and a sub gas engine for an inboard power source has been known. For example, Patent Document 1 discloses a ship 100 as shown in FIG.

Specifically, in the ship 100, the boil-off gas generated in the tank 110 that stores the liquefied natural gas is guided to the compressor 130 by the air supply line 121, and is compressed to a high temperature and high pressure by the compressor 130. The boil-off gas discharged from the compressor 130 is guided to the main gas engine (MEGI engine) for propulsion by the first supply line 122.

Further, the extracted gas extracted from the compressor 130 during compression is guided to the sub gas engine (DF engine) for the onboard power supply by the second supply line 131, and the GCU (Gas Combustion Unit:) is guided by the third supply line 132. It is guided to the gas combustion device). Therefore, when the amount of boil-off gas generated exceeds the amount consumed by the main gas engine, it is possible to supply the extracted gas having the difference between them as fuel gas to the sub gas engine and the GCU for combustion.

Japanese Unexamined Patent Publication No. 2015-505941

By the way, the pressure of the fuel gas supplied to the sub gas engine needs to be maintained within the allowable range required by the sub gas engine. However, if the GCU trips while the extracted gas is being supplied to the secondary gas engine and the GCU as fuel gas, the pressure in the second supply line 131 rises sharply and the pressure of the fuel gas supplied to the secondary gas engine May exceed the permissible range.

Therefore, an object of the present invention is to ensure that the pressure of the fuel gas supplied to the sub gas engine can be maintained within an allowable range.

In order to solve the above problems, the present invention comprises a main gas engine for propulsion, a tank for storing liquefied natural gas, an air supply line for guiding boil-off gas generated in the tank to a compressor, and the compressor. The first supply line that guides the boil-off gas discharged from the main gas engine to the main gas engine, the extraction line that guides the extraction gas extracted during compression from the compressor to the header, and the header and the second supply line are connected. , A secondary gas engine for onboard power supply, a GCU connected to the header by a third supply line, a GCU control device that controls the GCU, and a return with a flow control valve connected from the header to the tank. A line and a control device for controlling the flow rate control valve are provided, and the control device increases the opening degree of the flow rate control valve by a predetermined amount when receiving a GCU trip signal from the GCU control device. To provide a vessel.

According to the above configuration, if the GCU trips while the extracted gas is being supplied as fuel gas to the sub gas engine and the GCU via the header, the opening of the flow control valve is increased and the extracted gas is returned to the return line. It is returned from the header to the tank through. Therefore, the pressure of the fuel gas supplied to the sub gas engine can be surely kept within the permissible range.

The return line and the flow control valve are a first return line and a first flow control valve, respectively, and the ship guides the liquefied natural gas discharged from the pump arranged in the tank to the forced vaporizer. A second flow control valve provided with a liquid feeding line, a header supply line that guides the vaporized gas generated by the forced vaporizer to the header, and a second flow rate control valve that branches off from the header supply line and connects to the tank. Further including a return line, the integrated control device increases the opening degree of the first flow rate control valve by a predetermined amount when receiving a GCU trip signal from the GCU control device, and controls the second flow rate. The opening degree of the valve may be increased by a predetermined amount. According to this configuration, even if the GCU trips in a situation where a large amount of fuel gas is supplied to the GCU, the fuel gas can be stably supplied to the sub gas engine.

For example, the integrated control device may determine the predetermined amount based on the fuel gas supply amount to the GCU immediately before receiving the GCU trip signal.

According to the present invention, the pressure of the fuel gas supplied to the sub gas engine can be surely kept within an allowable range.

It is a schematic block diagram of the ship which concerns on one Embodiment of this invention. It is a schematic block diagram of a ship of a modification. It is a schematic block diagram of a conventional ship.

FIG. 1 shows a ship 1 according to an embodiment of the present invention. The ship 1 includes a tank 11 for storing liquefied natural gas (hereinafter referred to as LNG), a main gas engine 13 for propulsion, and a sub gas engine 17 for an inboard power source.

In the illustrated example, only one tank 11 is provided, but a plurality of tanks 11 may be provided (for example, the ship 1 may be an LNG carrier). Further, in the illustrated example, one main gas engine 13 and one sub gas engine 17 are provided, but a plurality of main gas engines 13 may be provided, or a plurality of sub gas engines 17 may be provided.

The main gas engine 13 may drive the screw propeller (not shown) directly by rotation (mechanical propulsion), or may indirectly drive the screw propeller indirectly via a generator and a motor (electricity). Promotion).

In the present embodiment, the main gas engine 13 is a reciprocating engine having a medium or high fuel gas injection pressure. The main gas engine 13 may be a gas-only combustion engine that burns only fuel gas, or a dual fuel engine that burns one or both of fuel gas and fuel oil (for example, MEGI engine). However, the main gas engine 13 may be a reciprocating engine having a low fuel gas injection pressure. Alternatively, the main gas engine 13 may be a gas turbine engine.

The sub gas engine 17 is a reciprocating engine having a low fuel gas injection pressure, and is connected to a generator (not shown). The sub-gas engine 17 may be a gas-only combustion engine that burns only fuel gas, or a dual fuel engine that burns one or both of fuel gas and fuel oil.

Boil-off gas (hereinafter referred to as BOG) generated in the tank 11 due to natural heat input is mainly supplied to the main gas engine 13 as fuel gas, and LNG is forcibly supplied to the sub gas engine 17 as fuel gas. The vaporized gas (hereinafter referred to as VG) vaporized in is mainly supplied.

Specifically, the tank 11 is connected to the compressor 12 by the air supply line 21, and the compressor 12 is connected to the main gas engine 13 by the first supply line 22. Further, a pump 14 is arranged in the tank 11, and the pump 14 is connected to the forced vaporizer 15 by a liquid feeding line 31. The forced vaporizer 15 is connected to the header 16 by the header supply line 32, the header 16 is connected to the sub gas engine 17 by the second supply line 51, and is connected to the GCU 18 by the third supply line 52. ing. Further, the header 16 is connected to the compressor 12 by an extraction line 43.

The air supply line 21 guides the BOG generated in the tank 11 to the compressor 12. The compressor 12 compresses the BOG to medium pressure or high pressure. The first supply line 22 guides the BOG discharged from the compressor 12 to the main gas engine 13.

The liquid feeding line 31 guides the LNG discharged from the pump 14 to the forced vaporizer 15. The liquid feeding line 31 is provided with a flow rate control valve 36 whose opening degree can be changed. The forced vaporizer 15 forcibly vaporizes LNG to generate VG. The header supply line 32 guides the VG generated by the forced vaporizer 15 to the header 16.

The pump 14 discharges LNG so that the pressure of the VG generated by the forced vaporizer 15 (that is, the outlet pressure of the forced vaporizer 15) is higher than the fuel gas injection pressure of the sub gas engine 17. However, a compressor may be provided in the header supply line 32, and the compressor may raise the pressure of the VG higher than the fuel gas injection pressure of the sub gas engine 17 instead of the pump 14.

The header supply line 32 is provided with a cooler 33, a gas-liquid separator 34, and a heater 35 in this order from the upstream side. The cooler 33 cools the VG generated by the forced vaporizer 15. Most of the heavy components in the VG (eg, ethane, propane, butane, etc.) become liquid when cooled by the cooler 33, are removed by the gas-liquid separator 34, and are returned to the tank 11. As a result, VG having a high methane value is supplied to the sub gas engine 17. The heater 35 heats the VG that has passed through the gas-liquid separator 34.

Further, the header supply line 32 is connected to the air supply line 21 by the supply line 41. In the illustrated example, the replenishment line 41 branches from the header supply line 32 between the cooler 33 and the gas-liquid separator 34 and joins the air supply line 21, but the replenishment line 41 and the gas-liquid separator 34 It may branch from the header supply line 32 between the heaters 35. The replenishment line 41 is provided with a flow rate control valve 42 whose opening degree can be changed.

The header 16 functions as a buffer for fuel gas supplied to the sub gas engine 17 and the GCU 18. The header 16 may be a container or may be composed of an expanded portion of the pipe.

The extraction line 43 guides the extraction gas (hereinafter referred to as BG) extracted from the compressor 12 during compression to the header 16. The extraction line 43 is provided with a flow rate control valve 44 whose opening degree can be changed. When the flow control valve 44 is closed, the fuel gas in the header 16 is only VG, and when the flow control valve 44 is opened, the fuel gas in the header 16 is only a mixed gas of VG and BG or BG.

The second supply line 51 guides the fuel gas from the header 16 to the sub gas engine 17, and the third supply line 52 guides the fuel gas from the header 16 to the GCU 18. The third supply line 52 is provided with a flow rate control valve 53 for adjusting the fuel gas supply amount to the GCU 18.

Further, in the present embodiment, the first return line 61 and the second return line 63 are provided. The first return line 61 is connected from the header 16 to the tank 11, and the second return line 63 is branched from the header supply line 32 and connected to the tank 11. In the illustrated example, the second return line 63 branches from the header supply line 32 between the gas-liquid separator 34 and the heater 35, but the second return line 63 is the cooler 33 and the gas-liquid separator 34. It may branch from the header supply line 32 between them.

The discharge port, which is the downstream end of the first return line 61, may be located above the liquid level of LNG in the tank 11 or below the liquid level. Similarly, the discharge port at the downstream end of the second return line 63 may be located above the liquid level of LNG in the tank 11 or below the liquid level.

The first return line 61 is provided with a flow control valve 62 (corresponding to the first flow control valve of the present invention) whose opening degree can be changed, and the second return line 63 has a changeable opening degree. A flow rate control valve 64 (corresponding to the second flow rate control valve of the present invention) is provided. These flow rate control valves 62, 64 and the above-mentioned flow rate control valves 36, 42, 44 are controlled by the integrated control device 71. However, in FIG. 1, only some signal lines are drawn for the sake of simplification of the drawing.

For example, the integrated control device 71 has a memory such as a ROM or RAM and a CPU, and the program stored in the ROM is executed by the CPU. The integrated control device 71 is electrically connected to the first pressure gauge 81 and the second pressure gauge 82. The first pressure gauge 81 detects the pressure of the BOG flowing through the air supply line 21. The second pressure gauge 82 detects the pressure in the header 16.

Further, the integrated control device 71 transmits and receives various signals to and from the main gas engine control device 72, the sub gas engine control device 73, and the GCU control device 74. The main gas engine control device 72 controls the opening and closing of the fuel injection valve provided in the main gas engine 13, and the sub gas engine control device 73 controls the opening and closing of the fuel injection valve provided in the sub gas engine 17. To do. The GCU control device 74 controls the GCU 18 and the flow rate control valve 53.

The general control device 71 calculates the fuel gas consumption Q1 of the main gas engine 13 from the fuel gas amount request signal transmitted from the main gas engine control device 72, and the fuel gas amount transmitted from the sub gas engine control device 73. The fuel gas consumption Q2 of the sub gas engine 17 is calculated from the request signal. However, the general control device 71 may directly acquire the fuel gas consumption Q1 from the main gas engine control device 72, or directly acquire the fuel gas consumption Q2 from the sub gas engine control device 73. May be good.

Further, the integrated control device 71 calculates the available amount Qa of BOG based on the amount of LNG in the tank 11 and the pressure of BOG detected by the first pressure gauge 81. Specifically, the integrated control device 71 adds the pressure loss from the intake port, which is the upstream end of the air supply line 21, to the position of the first pressure gauge 81, to the BOG pressure detected by the first pressure gauge 81. Then, the pressure of the BOG in the tank 11 is calculated. However, the first pressure gauge 81 may be provided in the tank 11 and directly detect the pressure of the BOG in the tank 11. Then, the integrated control device 71 calculates the available amount Qa of BOG from the amount of LNG in the tank 11 and the pressure of BOG in the tank 11. For example, when the tank 11 is a cargo tank and the capacity of the tank 11 is very large, the amount of LNG in the tank 11 can be treated as a fixed value. On the other hand, when the capacity of the tank 11 is small, the tank 11 may be provided with a level meter for detecting the amount of LNG in the tank 11, and the amount of LNG in the tank 11 may be treated as a variable.

After calculating the usable amount Qa of the BOG, the integrated control device 71 determines the total fuel gas consumption Qt and the BOG, which is the sum of the fuel gas consumption Q1 of the main gas engine 13 and the fuel gas consumption Q2 of the sub gas engine 17. Compare the available amount Qa. When Qt> Qa, the integrated control device 71 sends the insufficient amount of LNG obtained by subtracting the available amount Qa of BOG from the total fuel gas consumption Qt so that it is supplied to the forced vaporizer 15 through the liquid feeding line 31. The flow rate control valve 36 provided in the liquid line 31 is controlled. The LNG return line 37 is branched from the liquid feed line 31 on the upstream side of the flow control valve 36, and the portion of the LNG discharged from the pump 14 that is limited by the flow control valve 36 is the LNG return line 37. It is returned to the tank 11 through.

Further, when Qt> Qa, the integrated control device 71 compares the available amount Qa of the BOG with the fuel gas consumption amount Q1 of the main gas engine 13. When Qa <Q1, the overall control device 71 fully closes the flow rate control valve 44 provided in the extraction line 43, and opens the flow rate control valve 42 provided in the supply line 41 to a predetermined opening degree. As a result, the BOG mixed with the VG at the confluence of the supply lines 41 in the air supply line 21 is supplied to the main gas engine 13 as fuel gas. On the other hand, only VG is supplied to the sub gas engine 17 as fuel gas. On the other hand, when Qa> Q1, the integrated control device 71 fully closes the flow rate control valve 42 and opens the flow rate control valve 44 to a predetermined opening degree. As a result, a mixed gas of VG and BG is supplied to the sub gas engine 17 as a fuel gas.

On the contrary, when Qt <Qa, the integrated control device 71 completely closes the flow rate control valve 36 provided in the liquid feeding line 31 after stopping the operation of the forced vaporizer 15. Further, the overall control device 71 fully closes the flow rate control valve 42 provided in the supply line 41 and opens the flow rate control valve 44 provided in the extraction line 43 to a predetermined opening degree. As a result, only BG is supplied to the sub gas engine 17 as fuel gas. However, instead of fully closing the flow control valve 36, the opening degree of the flow rate control valve 36 is set to the minimum opening degree at which the forced vaporizer 15 can continue to operate without stopping the operation of the forced vaporizer 15. Good.

Further, when Qt <Qa, the general control device 71 calculates the fuel gas supply amount Qg to the GCU 18 as the processing amount of the fuel gas to be processed by the GCU 18, and outputs a processing amount signal representing the calculated fuel gas supply amount Qg. It is transmitted to the GCU control device 74. The third supply line 52 is provided with a flow meter 83 on the downstream side of the flow control valve 53. The GCU control device 74 controls the flow rate control valve 53 so that the flow rate detected by the flow meter 83 is the fuel gas supply amount Qg represented by the processing amount signal transmitted from the control control device 71.

Further, the integrated control device 71 has a flow control valve 62 and a second return line 63 provided in the first return line 61 regardless of whether the total fuel gas consumption Qt is larger or smaller than the available amount Qa of the BOG. At least one of the flow control valves 64 provided in the above is controlled by feedback control so that the pressure in the header 16 detected by the second pressure gauge 82 becomes the target pressure.

When the GCU 18 trips, the GCU control device 74 transmits a GCU trip signal to the overall control device 71. When the integrated control device 71 receives the GCU trip signal from the GCU control device 74, the integrated control device 71 increases the opening degree of the first flow rate control valve 62 by a predetermined amount α and increases the opening degree of the second flow rate control valve 64 by a predetermined amount. Increase by β.

The integrated control device 71 determines the predetermined amounts α and β based on the fuel gas supply amount Qg calculated immediately before receiving the GCU trip signal. However, the actual fuel gas supply amount detected by the flow meter 83 is transmitted from the GCU control device 74 to the general control device 71, and is based on the actual fuel gas supply amount immediately before the general control device 71 receives the GCU trip signal. The predetermined amounts α and β may be determined.

As described above, in the ship 1 of the present embodiment, when the GCU 18 trips while the BG is being supplied as fuel gas to the sub gas engine 17 and the GCU 18 via the header 16, it is provided in the first return line 61. As the opening degree of the flow rate control valve 62 increases, the BG is returned from the header 16 to the tank 11 through the first return line 61. Therefore, the pressure of the fuel gas supplied to the sub-gas engine 17 can be reliably maintained within the permissible range required by the sub-gas engine 17.

Further, in the present embodiment, when the integrated control device 71 receives the GCU trip signal, not only the opening degree of the flow rate control valve 61 provided in the first return line 61 but also the flow rate provided in the second return line 62. Since the opening degree of the control valve 64 also increases, even if the GCU trips in a situation where a large amount of fuel gas is being supplied to the GCU 18, the fuel gas can be stably supplied to the sub gas engine 17.

(Modification example)
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, as shown in FIG. 2, depending on the type of ship 1, the pump 14, the liquid feeding line 31, the header supply line 32, and the second return line 63 may not be provided. In this case, the integrated control device 71 increases the opening degree of the first flow rate control valve 62 by a predetermined amount α when the GCU trip signal is received from the GCU control device 74.

Further, although not shown, a BOG return line provided with an expansion device, which branches from the first supply line 22 and connects to the tank 11, may be adopted. At this time, when Qa> Q1, the excess gas having the difference is first returned to the tank 11 through the BOG return line, and when the pressure in the tank 11 exceeds the allowable value, the flow rate provided in the extraction line 43 is provided. The control valve 44 may be opened.

1 Ship 11 Tank 12 Compressor 13 Main gas engine 14 Pump 15 Forced carburetor 16 Header 17 Secondary gas engine 18 GCU
21 Air supply line 22 1st supply line 31 Liquid supply line 32 Header supply line 43 Extraction line 51 2nd supply line 52 3rd supply line 61 1st return line 62 Flow control valve (1st flow control valve)
63 Second return line 64 Flow control valve (second flow control valve)
71 Integrated control device 74 GCU control device

Claims (4)

Main gas engine for propulsion and
A tank for storing liquefied natural gas and
An air supply line that guides the boil-off gas generated in the tank to the compressor,
A first supply line that guides the boil-off gas discharged from the compressor to the main gas engine, and
An extraction line that guides the extraction gas extracted from the compressor during compression to the header,
An auxiliary gas engine for inboard power supply connected to the header by a second supply line,
The GCU connected to the header by the third supply line,
The GCU control device that controls the GCU and
A return line with a flow control valve that connects the header to the tank,
The integrated control device for controlling the flow control valve is provided.
The integrated control device is a ship that increases the opening degree of the flow rate control valve by a predetermined amount when receiving a GCU trip signal from the GCU control device. The return line and the flow rate control valve are a first return line and a first flow control valve, respectively.
A liquid feeding line that guides the liquefied natural gas discharged from the pump arranged in the tank to the forced vaporizer, and
A header supply line that guides the vaporized gas generated by the forced vaporizer to the header, and
A second return line provided with a second flow control valve, which branches off from the header supply line and connects to the tank, is further provided.
When the integrated control device receives the GCU trip signal from the GCU control device, the integrated control device increases the opening degree of the first flow rate control valve by a predetermined amount and increases the opening degree of the second flow rate control valve by a predetermined amount. The vessel according to claim 1, which is to be increased. The ship according to claim 1, wherein the integrated control device determines the predetermined amount based on the fuel gas supply amount to the GCU immediately before receiving the GCU trip signal. The integrated control device determines the predetermined amount for the first flow rate control valve and the predetermined amount for the second flow rate control valve based on the fuel gas supply amount to the GCU immediately before receiving the GCU trip signal. , The vessel according to claim 2.

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