JP6722074B2 - 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 supply.

BACKGROUND ART Conventionally, ships including a main gas engine for propulsion and a sub gas engine for an inboard power supply are 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 liquefied natural gas is guided to the compressor 130 by the air supply line 121, and is compressed to 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 for propulsion (MEGI engine) by the first supply line 122.

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

JP, 2005-505941, A

By the way, the pressure of the fuel gas supplied to the sub gas engine needs to be kept within an allowable range required from the sub gas engine. However, when the amount of fuel gas supplied to the GCU sharply decreases due to a sudden load increase of the main gas engine while the extracted gas is supplied as fuel gas to the sub gas engine and the GCU, the second supply The pressure in the line 131 may suddenly increase, and the pressure of the fuel gas supplied to the auxiliary gas engine may exceed the allowable 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 reliably maintained within an allowable range.

In order to solve the above problems, the present invention provides 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. A first supply line for guiding boil-off gas discharged from the main gas engine to the main gas engine; an extraction line provided with a flow control valve for guiding the extraction gas extracted from the compressor during compression to the header; and the header. An auxiliary gas engine for inboard power supply connected by a second supply line, a GCU connected by the header and a third supply line, a pressure gauge for detecting pressure in the header, and a pressure gauge detected by the pressure gauge. While controlling the flow rate control valve by feedback control so that the pressure becomes the target pressure, the flow rate of the extraction gas flowing in the extraction line is preceded by the feedback control while the fuel gas supply amount to the GCU is reduced. And a control device for controlling the flow control valve so as to reduce the flow rate.

According to the above configuration, while the fuel gas supply amount to the GCU is decreasing, the extraction gas flow rate is decreased in advance so as to cancel the subsequent increase in the pressure in the header. Therefore, even if the amount of fuel gas supplied to the GCU sharply decreases due to a sudden load increase of the main gas engine, the pressure of the fuel gas supplied to the sub gas engine can be reliably maintained within the allowable range.

For example, in the compressor, at least one of a main flow path extending from an intake port to a discharge port, a plurality of compression mechanisms arranged in series on the main flow path, and a boil-off gas circulated in at least one of the plurality of compression mechanisms are circulated. One circulation passage and a flow control valve provided in the at least one circulation passage may be included, and the extraction line may be connected to the main passage between the plurality of compression mechanisms.

According to the present invention, the pressure of the fuel gas supplied to the sub gas engine can be reliably maintained within the allowable range.

It is a schematic structure figure of a vessel concerning one embodiment of the present invention. It is a schematic block diagram of the ship of a modification. It is a schematic block diagram of the conventional ship.

FIG. 1 shows a ship 1 according to an embodiment of the present invention. The marine vessel 1 includes a tank 11 that stores 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 supply.

Although only one tank 11 is provided in the illustrated example, 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 directly drive a screw propeller (not shown) for rotation (mechanical propulsion) or indirectly drive the screw propeller via a generator and a motor (electricity). Promotion).

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

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

Boil-off gas (hereinafter referred to as BOG) generated in the tank 11 by natural heat input is mainly supplied to the main gas engine 13 and LNG is compulsorily supplied to the sub gas engine 17 as fuel gas. The vaporized gas (hereinafter referred to as VG) that has been vaporized 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 sending line 31. The forced vaporizer 15 is connected to the header 16 by a header supply line 32, the header 16 is connected to the sub gas engine 17 by a second supply line 51, and is connected to the GCU 18 by a third supply line 52. ing. Further, the header 16 is connected to the compressor 12 by the extraction line 43.

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

The compressor 12 includes a main flow channel 12a extending from the suction port to the discharge port, and a plurality of (five in the illustrated example) compression mechanisms 12b arranged in series on the main flow channel 12a. Further, the compressor 12 includes at least one circulation path 12c that circulates BOG in at least one of the compression mechanisms 12b. In the present embodiment, the number of circulation paths 12c is the same as the number of compression mechanisms 12b. That is, the BOG discharged from each compression mechanism 12b is returned to the suction side of the compression mechanism 12b through the circulation path 12c. However, only one circulation path 12c may be provided so as to bypass all the compression mechanisms 12b. Each circulation path 12c is provided with a flow rate control valve 12d whose opening can be changed.

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

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

The header supply line 32 is provided with a cooler 33, a gas-liquid separator 34, and a heater 35 in 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 (for example, ethane, propane, butane) become liquid by cooling in the cooler 33, are removed in 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 auxiliary 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 is branched from the header supply line 32 between the cooler 33 and the gas-liquid separator 34 to join the air supply line 21, but the replenishment line 41 is connected to the gas-liquid separator 34. The header supply line 32 may be branched between the heaters 35. The supply line 41 is provided with a flow rate control valve 42 whose opening can be changed.

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

The extraction line 43 guides the extraction gas (hereinafter referred to as BG) extracted from the compressor 12 during the compression to the header 16. In the present embodiment, the extraction line 43 is connected to the main flow path 12a between the second stage compression mechanism 12b and the third stage compression mechanism 12b. The extraction line 43 is provided with a flow rate control valve 44 whose opening 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 the mixed gas of VG and BG or BG.

The second supply line 51 guides the fuel gas from the header 16 to the auxiliary 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 this embodiment, a first return line 61 and a 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 includes the cooler 33 and the gas-liquid separator 34. You may branch from the header supply line 32 in between.

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

The first return line 61 is provided with a flow rate control valve 62 whose opening can be changed, and the second return line 63 is provided with a flow rate control valve 64 whose opening can be changed. The flow rate control valves 62, 64 and the flow rate control valves 36, 42, 44 described above are controlled by the integrated control device 71. Further, the overall control device 71 also controls the flow rate control valve 12d of the compressor 12. However, in FIG. 1, only some of the signal lines are drawn for simplification of the drawing.

For example, the overall control device 71 has a memory such as a ROM and a RAM and a CPU, and a 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 opening/closing of a fuel injection valve provided in the main gas engine 13, and the sub gas engine control device 73 controls opening/closing of a 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 integrated control device 71 calculates the fuel gas consumption amount 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 amount Q2 of the sub gas engine 17 is calculated from the request signal. However, the integrated control device 71 may directly obtain the fuel gas consumption amount Q1 from the main gas engine control device 72 or directly obtain the fuel gas consumption amount Q2 from the sub gas engine control device 73. Good.

Further, the overall control device 71 calculates the usable 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 overall 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 overall control device 71 calculates the usable 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 available amount Qa of BOG, the overall control device 71 calculates the total fuel gas consumption Qt, which is the sum of the fuel gas consumption amount Q1 of the main gas engine 13 and the fuel gas consumption amount Q2 of the auxiliary gas engine 17, and the BOG. The available amount Qa is compared. In the case of Qt>Qa, the integrated control device 71 sends a shortage amount of LNG obtained by subtracting the usable amount Qa of BOG from the total fuel gas consumption amount Qt 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. An LNG return line 37 is branched from the liquid supply line 31 on the upstream side of the flow rate control valve 36, and a portion of the LNG discharged from the pump 14 that is limited by the flow rate control valve 36 is LNG return line 37. It is returned to the tank 11 through.

Further, in the case of Qt>Qa, the integrated control device 71 compares the available amount Qa of BOG with the fuel gas consumption amount Q1 of the main gas engine 13. When Qa<Q1, the integrated 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, BOG mixed with VG at the confluence of the supply line 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 the fuel gas. On the other hand, when Qa>Q1, the overall 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, the mixed gas of VG and BG is supplied as the fuel gas to the sub gas engine 17.

On the contrary, when Qt<Qa, the integrated control device 71 fully 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 replenishment 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 as fuel gas to the sub gas engine 17. However, instead of fully closing the flow control valve 36, the opening of the flow control valve 36 is set to the minimum opening at which the operation of the forced vaporizer 15 can be continued without stopping the operation of the forced vaporizer 15. Good.

Further, in the case of Qt<Qa, the overall control unit 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 the processing amount signal representing the calculated fuel gas supply amount Qg. It is transmitted to the GCU control unit 74. A flow meter 83 is provided on the third supply line 52 downstream 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 becomes the fuel gas supply amount Qg represented by the processing amount signal transmitted from the overall control device 71.

Further, the integrated control device 71, when opening the flow control valve 44 provided in the extraction line 43, regardless of whether the total fuel gas consumption amount Qt is larger or smaller than the BOG available amount Qa, the flow control valve 71 44 is controlled by feedback control so that the pressure in the header 16 detected by the second pressure gauge 82 becomes the target pressure.

Further, the integrated control device 71 performs feedforward control based on the calculated fuel gas supply amount Qg to the GCU 18 while performing feedback control. Specifically, the overall control device 71 controls the flow rate control valve 44 so as to reduce the flow rate of BG flowing through the extraction line 43 prior to the feedback control while the fuel gas supply amount Qg decreases. That is, the overall control device 71 decreases the opening degree of the flow rate control valve 44 as the fuel gas supply amount Qg decreases. Further, the overall control device 71 reduces the opening degree of the flow rate control valve 44 and simultaneously increases the opening degree of at least one of the flow rate control valves 12b of the compressor 12.

When the pressure in the header 16 detected by the second pressure gauge 82 exceeds the upper limit even if the above-described control is performed, the integrated control device 71 causes the flow control valve 62 provided in the first return line 61 to operate. At least one of the flow rate control valves 64 provided in the second return line 63 is opened.

As described above, in the marine vessel 1 of the present embodiment, while the fuel gas supply amount Qg to the GCU 18 is decreasing, the BG flow rate is decreased in advance so as to cancel the subsequent increase in the pressure in the header 16. .. Therefore, even if the fuel gas supply amount Qg to the GCU 18 sharply decreases due to a sudden load increase of the main gas engine 13, the pressure of the fuel gas supplied to the sub gas engine 17 is requested from the sub gas engine 17. Can be reliably kept within the allowable range.

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

For example, the integrated control device 71 does not necessarily have to perform the feedforward control based on the calculated fuel gas supply amount Qg to the GCU 18. The actual fuel gas supply amount detected by the flow meter 83 may be transmitted from the GCU control device 74 to the integrated control device 71, and the integrated control device 71 may perform the feedforward control based on the actual fuel gas supply amount.

Further, as shown in FIG. 2, the first return line 61 may be omitted. Further, depending on the type of the ship 1, the pump 14, the liquid supply line 31, the header supply line 32, and the second return line 63 may be omitted.

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, if Qa>Q1, surplus gas of 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 The control valve 44 may be opened.

1 Ship 11 Tank 12 Compressor 12a Main flow path 12b Compression mechanism 12c Circulation path 12d Flow control valve 13 Main gas engine 16 Header 17 Sub gas engine 18 GCU
21 Air Supply Line 22 First Supply Line 43 Extraction Line 44 Flow Control Valve 51 Second Supply Line 52 Third Supply Line 71 Integrated Control Device

Claims (2)

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,
A first supply line for guiding boil-off gas discharged from the compressor to the main gas engine;
An extraction line provided with a flow rate control valve, which guides the extraction gas extracted from the compressor during compression to the header,
A sub-gas engine for power supply onboard, connected by the header and a second supply line;
A GCU connected to the header by a third supply line,
A pressure gauge for detecting the pressure in the header,
While controlling the flow rate control valve by feedback control so that the pressure detected by the pressure gauge becomes a target pressure, the flow rate of the extraction gas flowing through the extraction line is controlled while the fuel gas supply amount to the GCU decreases. A controller that controls the flow control valve so as to decrease prior to the feedback control;
Equipped with a ship. The compressor has a main flow path extending from an intake port to a discharge port, a plurality of compression mechanisms arranged in series on the main flow path, and at least one circulation for circulating boil-off gas to at least one of the plurality of compression mechanisms. And a flow control valve provided in the at least one circuit,
The marine vessel according to claim 1, wherein the extraction line is connected to the main flow path between the plurality of compression mechanisms.

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