JP2018103954A - Ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely keep a pressure of fuel gas supplied to an auxiliary gas engine within an allowable range.SOLUTION: A ship comprises: a compressor including a main flow passage, upstream side compression mechanisms, upstream side circulation passages, and upstream side bypass valves; an air feed line introducing BOG (Boil Off Gas), which is generated in a tank storing LNG, to the compressor; a first supply line introducing the BOG from the compressor to a main gas engine for propulsion; an extraction line that introduces extracted gas from the compressor to a header and is provided with an extraction valve; an auxiliary gas engine for an inboard power supply connected to a header through a second supply line; and a control device that controls the extraction valve so that a pressure in the header detected by a header pressure gauge becomes a target pressure, and while controlling the upstream side bypass valves by feedback control so that discharge pressures of the upstream side compression mechanisms detected by compression mechanism pressure gauges become target pressures, and controls the upstream side bypass valves prior to the feedback control on the basis of an opening degree of the extraction valve.SELECTED DRAWING: Figure 1

Description

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

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

  Specifically, in the ship 100, boil-off gas generated in the tank 110 that stores liquefied natural gas is guided to the compressor 140 by the air supply line 121 and is compressed to high temperature and high pressure by the compressor 140. The boil-off gas discharged from the compressor 140 is guided to the propulsion main gas engine (MEGI engine) through the first supply line 122.

  The extracted gas extracted from the compressor 140 during the compression is guided to the sub-gas engine (DF engine) for inboard power by the extraction line 131 and the second supply line 132, and the extraction line 131 and the third supply line. 133 leads to GCU (Gas Combustion Unit).

  The compressor 140 is a multistage compressor including five compression mechanisms 161 to 165 arranged in series on the main flow path 150. In FIG. 3, the extraction line 131 branches from the main flow path 150 between the second compression mechanism 162 and the third compression mechanism 163.

Special table 2015-505941 gazette

  By the way, the pressure of the fuel gas supplied to the auxiliary gas engine needs to be maintained within an allowable range required from the auxiliary gas engine.

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

  In order to solve the 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 leading the boil-off gas discharged from the main gas engine, an extraction line provided with an extraction valve for guiding the extracted gas extracted during compression from the compressor to the header, the header and the first The auxiliary gas engine for ship power supply connected by two supply lines, a header pressure gauge for detecting the pressure in the header, and the extraction valve so that the pressure detected by the header pressure gauge becomes a target pressure. A control device for controlling the compressor, the compressor extending from the suction port to the discharge port, the main flow path where the extraction line branches, and the upstream side from the branch point of the extraction line At least one upstream compression mechanism provided in the main flow path; at least one upstream circulation path bypassing the at least one upstream compression mechanism; and at least one upstream path provided in the at least one upstream circulation path And at least one compression mechanism pressure gauge for detecting a discharge pressure of the at least one upstream compression mechanism, and the control device is detected by the at least one compression mechanism pressure gauge. The at least one upstream bypass valve is controlled prior to the feedback control while the opening degree of the extraction valve is increased while the at least one upstream bypass valve is controlled by feedback control so that the target pressure becomes the target pressure. While the opening of the valve is reduced and the opening of the extraction valve is reduced, the less Even so that the opening of one of the upstream bypass valve is increased, controlling said at least one upstream bypass valve, to provide a marine vessel.

  According to said structure, while the opening degree of an extraction valve increases, the opening degree of at least 1 upstream bypass valve reduces so that the fall of the discharge pressure of a subsequent at least 1 upstream compression mechanism may be canceled, While the opening degree of the extraction valve decreases, the opening degree of the at least one upstream bypass valve increases so as to cancel the subsequent increase in the discharge pressure of the at least one upstream compression mechanism. Therefore, even if the extraction valve is operated with good response, fluctuations in the discharge pressure of at least one upstream compression mechanism can be suppressed to a small level. In addition, by operating the extraction valve with good response, the pressure of the fuel gas supplied to the auxiliary gas engine can be reliably maintained within the allowable range.

  The ship may further include a GCU connected by the header and a third supply line. According to this configuration, it is possible to cope with a sudden change in the pressure in the header caused by either a sudden change in the load of the auxiliary gas engine or a sudden change in the processing gas amount of the GCU.

  The ship includes a liquid feed line that leads liquefied natural gas discharged from a pump disposed in the tank to a forced vaporizer, and a header supply line that leads vaporized gas generated by the forced vaporizer to the header. And may be further provided. According to this configuration, the fuel gas can be stably supplied to the auxiliary gas engine.

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

It is a schematic structure figure of a ship 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 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 inboard power.

  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). 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 or a plurality of sub gas engines 17 may be provided.

  The main gas engine 13 may directly rotate and drive a screw propeller (not shown) (mechanical propulsion), or may indirectly rotate and 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 having a high fuel gas injection pressure. 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 whose fuel gas injection pressure is medium or low. Alternatively, the main gas engine 13 may be a gas turbine engine.

  The auxiliary gas engine 17 is a reciprocating engine having a low fuel gas injection pressure, and is connected to a generator (not shown). The auxiliary gas engine 17 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.

  The main gas engine 13 is mainly supplied with boil-off gas (hereinafter referred to as “BOG”) generated in the tank 11 by natural heat input as the fuel gas, and the sub-gas engine 17 is forcedly supplied with LNG as the fuel gas. Vaporized gas (hereinafter referred to as VG) is mainly supplied.

  Specifically, the tank 11 is connected to the compressor 12 by an air supply line 21, and the compressor 12 is connected to the main gas engine 13 by a first supply line 22. Further, a pump 14 is disposed in the tank 11, and the pump 14 is connected to the forced vaporizer 15 by a liquid feed line 31. The forced vaporizer 15 is connected to the header 16 by a header supply line 32, and the header 16 is connected to the auxiliary 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 an extraction line 43.

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

  The liquid feed line 31 guides LNG discharged from the pump 14 to the forced vaporizer 15. 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 such 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 auxiliary gas engine 17. However, a compressor may be provided in the header supply line 32, and the compressor may make the VG pressure higher than the fuel gas injection pressure of the auxiliary 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 order from the upstream side. The cooler 33 cools the VG generated by the forced vaporizer 15. Most of heavy components in VG (for example, ethane, propane, butane, etc.) become liquid by cooling in the cooler 33, removed by the gas-liquid separator 34, and returned to the tank 11. As a result, VG having a high methane number is supplied to the auxiliary gas engine 17. The heater 35 heats the VG that has passed through the gas-liquid separator 34 to a temperature suitable for supply to the auxiliary gas engine 17.

  The header supply line 32 is connected to the air supply line 21 by a 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 merges with the air supply line 21, but the replenishment line 41 is connected to the gas-liquid separator 34. You may branch from the header supply line 32 between the heaters 35. The supply line 41 is provided with a supply valve 42.

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

  The extraction line 43 guides extracted gas (hereinafter referred to as BG) extracted during compression from the compressor 12 to the header 16. The extraction line 43 is provided with an extraction valve 44. When the extraction valve 44 is closed, the fuel gas in the header 16 is only VG, and when the extraction 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. A supply amount adjustment valve 53 is provided in the third supply line 52.

  The replenishment valve 42, the extraction valve 44, and the supply amount adjustment valve 53 described above are controlled by the control device 6. However, in FIG. 1, only a part of the signal lines is drawn for simplification of the drawing. For example, the control device 6 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 control device 6 may be a single device or may be divided into a plurality of devices.

  The control device 6 is electrically connected to a BOG pressure gauge 61 provided on the air supply line 21 and a header pressure gauge 62 provided on the header 16. The BOG pressure gauge 61 detects the pressure of the BOG in the air supply line 21, and the header pressure gauge 62 detects the pressure in the header 16.

  The control device 6 calculates the available amount Qa of BOG based on the amount of LNG in the tank 11 and the BOG pressure detected by the BOG pressure gauge 61. Specifically, the control device 6 adds the pressure loss from the intake port at the upstream end of the air supply line 21 to the position of the BOG pressure gauge 61 to the pressure of the BOG detected by the BOG pressure gauge 61, The pressure of BOG in the tank 11 is calculated. However, the BOG pressure gauge 61 may be provided in the tank 11 and directly detect the pressure of the BOG in the tank 11. Then, the control device 6 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 handled as a fixed value. On the other hand, when the capacity of the tank 11 is small, a level meter that detects the amount of LNG in the tank 11 may be provided 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 BOG, the control device 6 compares the fuel gas consumption amount Q1 of the main gas engine 13 with the usable amount Qa of BOG. Then, the control device 6 opens the supply valve 42 when Qa <Q1, and opens the extraction valve 44 when Qa> Q1. When opening the extraction valve 44, the control device 6 controls the extraction valve 44 by feedback control so that the pressure detected by the header pressure gauge 62 becomes the target pressure.

  When Qa> Q1, the control device 6 determines that the BOG usable amount Qa 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. Compare with quantity Qt. When Qa> Qt, the control device 6 calculates the fuel gas supply amount to the GCU 18 and opens the supply amount adjustment valve 53. At this time, the control device 6 may stop the operation of the forced vaporizer 15 (return LNG discharged from the pump 14 to the tank 11 through a return line (not shown)) and fully close the supply valve 42.

  Next, the compressor 12 will be described in detail.

  The compressor 12 includes a main flow path 7 extending from the suction port 12a to the discharge port 12b. The extraction line 43 described above branches off from the main flow path 7. The compressor 12 includes two upstream compression mechanisms 71 and 72 provided in the main flow path 7 on the upstream side of the branch point of the extraction line 43, and the main flow path 7 on the downstream side of the branch point of the extraction line 43. Includes three downstream compression mechanisms 73 to 75. However, the number of upstream compression mechanisms may be one, or may be three or more. Further, the number of downstream side compression mechanisms may be one or two, or may be four or more.

  Further, the compressor 12 includes two upstream circulation paths 81 and 82 that bypass the upstream compression mechanisms 71 and 72, respectively, and three downstream circulation paths 83 to 85 that bypass the downstream compression mechanisms 73 to 75, respectively. Including. Upstream bypass valves 91 and 92 are provided in the upstream circulation paths 81 and 82, respectively, and downstream bypass valves 93 to 95 are provided in the downstream circulation paths 83 to 85, respectively. For this reason, the BOG discharged from each of the compression mechanisms 71 to 75 can be returned to the suction side of the compression mechanism and circulated. That is, each of the bypass valves 91 to 95 defines the circulation amount of the corresponding compression mechanism (71 to 75).

  The main flow path 7 is provided with compression mechanism pressure gauges 63 to 67 on the discharge side of the compression mechanisms 71 to 75, respectively. Each of the compression mechanism pressure gauges 63 to 67 detects the discharge pressure of the corresponding compression mechanism (71 to 75). For example, the compression mechanism pressure gauge 63 detects the discharge pressure of the upstream compression mechanism 71. The control device 6 described above is electrically connected to these compression mechanism pressure gauges 63 to 67. The control device 6 controls the bypass valves 91 to 95 by feedback control so that each of the discharge pressures of the compression mechanisms 71 to 75 detected by the compression mechanism pressure gauges 63 to 67 becomes the target pressure.

  Furthermore, the control device 6 performs feedforward control on the upstream bypass valves 91 and 92 based on the opening degree of the extraction valve 44 described above while performing feedback control. Specifically, the control device 6 sets the upstream bypass valves 91 and 92 so that the upstream bypass valves 91 and 92 are decreased before the feedback control while the opening of the extraction valve 44 is increased. To control. That is, the control device 6 decreases the opening degree of the upstream bypass valves 91 and 92 as the opening degree of the extraction valve 44 increases.

  On the contrary, while the opening degree of the extraction valve 44 decreases, the control device 6 controls the upstream bypass valves 91 and 92 so that the opening degree of the upstream bypass valves 91 and 92 increases prior to the feedback control. Control. That is, the control device 6 increases the opening degrees of the upstream bypass valves 91 and 92 as the opening degree of the extraction valve 44 decreases.

  When the feedforward control is not performed, when the extraction valve 44 is operated with good response to the pressure in the header 16, only the feedback control of the bypass valves 91 to 95 based on the discharge pressure of the compression mechanisms 71 to 75 is performed. Without being able to cope with this, the discharge pressures of the upstream compression mechanisms 71 and 72 vary greatly.

  On the other hand, in the ship 1 of this embodiment, while the opening degree of the extraction valve 44 is increased, the upstream bypass valves 91 and 92 are configured so as to cancel the subsequent decrease in the discharge pressure of the upstream compression mechanisms 71 and 72. While the opening degree decreases and the opening degree of the extraction valve 44 decreases, the opening degree of the upstream bypass valves 91 and 92 increases so as to cancel the subsequent increase in the discharge pressure of the upstream compression mechanisms 71 and 72. Therefore, even if the extraction valve 44 is operated with good response to the pressure in the header 16, fluctuations in the discharge pressures of the upstream compression mechanisms 71 and 72 can be suppressed. In addition, by operating the extraction valve 44 with good response, the pressure of the fuel gas supplied to the auxiliary gas engine 17 can be reliably maintained 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 GCU 18 may not be provided. However, if the GCU 18 is connected to the header 16 by the third supply line 52 as in the above-described embodiment, a sudden change in the load of the secondary gas engine 17 and a sudden change in the processing gas amount of the GCU 18 (for example, a trip of the GCU 18) It is possible to cope with a sudden change in pressure in the header 16 caused by either of the above.

  Further, as shown in FIG. 2, depending on the type of the ship 1, the pump 14, the liquid feeding line 31, the forced vaporizer 15, and the header supply line 32 may not be provided. However, if they are present as in the above-described embodiment, the fuel gas can be stably supplied to the auxiliary gas engine 17.

  Although not shown, a BOG return line provided with an expansion device that branches from the first supply line 22 and connects to the tank 11 may be employed.

DESCRIPTION OF SYMBOLS 1 Ship 11 Tank 12 Compressor 12a Intake port 12b Discharge port 13 Main gas engine 14 Pump 15 Forced vaporizer 16 Header 17 Sub gas engine 18 GCU
DESCRIPTION OF SYMBOLS 21 Air supply line 22 1st supply line 31 Liquid supply line 32 Header supply line 51 2nd supply line 52 3rd supply line 6 Control apparatus 62 Header pressure gauge 63-67 Compression mechanism pressure gauge 7 Main flow path 71,72 Upstream compression Mechanism 81, 82 Upstream circulation path 91, 92 Upstream bypass valve

Claims (3)

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 the compressor;
A first supply line for guiding boil-off gas discharged from the compressor to the main gas engine;
An extraction line provided with an extraction valve that guides the extracted gas extracted during compression from the compressor to the header;
A sub-gas engine for ship power connected to the header by a second supply line;
A header pressure gauge for detecting the pressure in the header;
A control device that controls the extraction valve so that the pressure detected by the header pressure gauge becomes a target pressure, and
The compressor includes a main flow path that branches from the suction port to the discharge port, where the extraction line branches, and at least one upstream compression mechanism that is provided in the main flow path upstream of the branch point of the extraction line; Including at least one upstream circulation path that bypasses the at least one upstream compression mechanism; and at least one upstream bypass valve provided in the at least one upstream circulation path;
And further comprising at least one compression mechanism pressure gauge for detecting a discharge pressure of the at least one upstream compression mechanism,
The control device increases the opening of the extraction valve while controlling the at least one upstream bypass valve by feedback control so that the pressure detected by the at least one compression mechanism pressure gauge becomes a target pressure. The opening of the at least one upstream bypass valve is reduced prior to the feedback control, and the at least one upstream bypass valve is prior to the feedback control while the opening of the extraction valve is reduced. A ship that controls the at least one upstream bypass valve so that the opening of the is increased.   The ship according to claim 1, further comprising a GCU connected to the header by a third supply line. A liquid feed line for guiding liquefied natural gas discharged from a pump disposed in the tank to a forced vaporizer;
The ship according to claim 1, further comprising a header supply line that guides the vaporized gas generated by the forced vaporizer to the header.

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