JP6423652B2 - Ship - Google Patents

Description

  The present invention relates to a ship equipped with a diesel engine that uses gas as fuel.

  Conventionally, in a ship, a diesel engine using heavy oil as a fuel has been used as a main engine for propulsion. In recent years, it has been proposed to use a diesel engine that uses gas as a fuel as a propulsion main engine. For example, Patent Document 1 discloses a marine diesel engine and a gas supply system that supplies fuel gas to the diesel engine.

  Specifically, in the gas supply system disclosed in Patent Document 1, the compressor is connected to a tank that stores fuel gas, and the gas compressed by the compressor is supplied to the diesel engine.

JP 2008-202550 A

  The fuel gas supplied to the diesel engine has a high pressure (injection pressure) of, for example, 15 to 30 MPa in absolute pressure in order to enable injection into compressed air. The compressor mentioned above sends out gas so that the gas discharged from the said compressor may become the injection pressure to a diesel engine.

  However, when the downstream side of the compressor is at a low pressure of about atmospheric pressure, it takes a considerable time (for example, 5 to 10 minutes) until the gas discharged from the compressor reaches the injection pressure to the diesel engine. ). For this reason, even if the operator wants to start gas operation with a diesel engine, gas operation cannot be performed immediately. Therefore, it is desired to maintain a state in which the gas discharged from the compressor becomes the injection pressure to the diesel engine, that is, a standby state, before the gas operation.

  For example, when a diesel engine uses so-called binary fuel of gas and oil as fuel, oil should be used as fuel at low loads such as when entering and leaving a port, and gas should be used as fuel during high loads such as during offshore voyages. Is assumed. In this case, if the standby state is maintained during the oil operation, the oil operation can be quickly switched to the gas operation.

  In the standby state, for example, a compressor including an unload valve is used, the compressor is continuously operated before gas operation, and the gas discharged from the compressor becomes an injection pressure to the diesel engine. This can be realized by opening the unload valve to an appropriate opening so that the injection pressure is maintained. However, a large amount of electric power is consumed to continue operating a compressor having a large compression ratio that enables boosting up to the injection pressure to the diesel engine.

  Then, an object of this invention is to provide the ship which can maintain the standby state before gas operation, suppressing power consumption.

  In order to solve the above problems, a ship according to one aspect of the present invention is connected to the tank via a diesel engine that uses gas as fuel, a tank that stores liquefied gas, and a first supply line. And a compressor connected to the diesel engine via a second supply line for compressing the vaporized gas of the liquefied gas, and provided in the second supply line, opened during gas operation of the diesel engine, The changeover valve that is closed except during the gas operation, and the compressor is stopped in a standby state in which the gas discharged from the compressor before the gas operation becomes the injection pressure to the diesel engine. And a control device.

  According to the above configuration, since the compressor is usually provided with a check valve at the discharge port and gas backflow is impossible, the injection pressure is reduced downstream from the check valve of the compressor by stopping the compressor. It is maintained and the standby state can be maintained. And by stopping the compressor in the standby state, the power consumption in the standby state can be suppressed.

  A ship according to another aspect of the present invention is connected to the tank via a diesel engine that uses gas as fuel, a tank that stores liquefied gas, and a first supply line, and via a second supply line. A compressor that is connected to the diesel engine and compresses the gas vaporized from the liquefied gas, and includes a circulation path that circulates the gas to be discharged inside, and an unload valve provided in the circulation path. And a switching valve provided in the second supply line that is opened during gas operation of the diesel engine and is closed except during the gas operation, and gas discharged from the compressor before the gas operation is In the standby state, which is the injection pressure to the diesel engine, the unload valve is opened to an opening larger than the reference opening for maintaining the injection pressure. And a control device, and wherein the.

  According to the above configuration, since the compressor is usually provided with a check valve at the discharge port and gas backflow is impossible, the opening degree of the unload valve should be larger than the reference opening degree in the standby state. Thus, gas is no longer discharged from the discharge port of the compressor, and the injection pressure is held downstream from the check valve of the compressor. Thereby, the standby state can be maintained. Moreover, the load of a compressor falls by making the opening degree of an unload valve larger than a reference opening degree in a standby state. Thereby, power consumption in the standby state can be suppressed.

  Each of the above ships further includes a holding valve that is provided in an upstream portion of the switching valve in the second supply line and holds the gas of the injection pressure between the switching valve in the standby state. May be. According to this configuration, it is possible to reliably hold the injection pressure gas at least between the holding valve and the switching valve.

  For example, the holding valve may be a check valve. Alternatively, the holding valve may be an on-off valve that is closed in the standby state.

  The diesel engine uses gas and oil as fuel, and oil operation of the diesel engine may be performed in the standby state. According to this configuration, it is possible to quickly switch from oil operation to gas operation.

  When the compressor is stopped in the standby state, the ship further includes a pressure gauge that detects a pressure in a portion upstream of the switching valve in the second supply line, and the control device is in the standby state, When the pressure detected by the pressure gauge falls below a threshold value smaller than the injection pressure, the compressor may be restarted. According to this configuration, the gas discharged from the compressor in the standby state can be maintained near the injection pressure to the diesel engine.

  When the opening degree of the unload valve is made larger than the reference opening degree in the standby state, the ship further includes a pressure gauge that detects a pressure in an upstream portion of the switching valve in the second supply line, The control device may reduce the opening of the unload valve below the reference opening when the pressure detected by the pressure gauge falls below a threshold smaller than the injection pressure during the standby state. Good. According to this configuration, the gas discharged from the compressor in the standby state can be maintained near the injection pressure to the diesel engine.

  For example, the diesel engine may be a two-cycle engine as a main engine for propulsion.

  According to the present invention, it is possible to maintain a standby state before gas operation while suppressing power consumption.

It is a schematic structure figure showing some ships concerning a 1st embodiment of the present invention. It is a schematic block diagram which shows a part of ship which concerns on 2nd Embodiment of this invention. It is a schematic block diagram which shows a part of ship which concerns on other embodiment.

(First embodiment)
FIG. 1 shows a part of a ship 1A according to the first embodiment of the present invention. This ship 1A is equipped with a tank 2 that stores liquefied gas and a diesel engine 6 that uses the gas obtained by vaporizing the liquefied gas as fuel.

For example, the ship 1A is a liquefied gas carrier ship, and the tank 2 is at least one of large transport tanks arranged in the ship length direction. For example, the liquefied gas is LNG, LPG (liquefied petroleum gas), LH ₂ (liquefied hydrogen), or the like. However, the ship 1A is not necessarily a liquefied gas carrier, and may be a ship for other purposes. The tank 2 may be a fuel dedicated tank.

  In the present embodiment, the diesel engine 6 is a two-cycle engine as a propulsion main machine that drives the propeller 61. In the present embodiment, the diesel engine 6 is a dual fuel engine that uses gas and oil as fuel. That is, the diesel engine 6 has a gas fuel injection valve and an oil fuel injection valve (both not shown) provided in each of the plurality of cylinders. Gas is supplied to the gas fuel injection valve from the gas supply system 10, and oil is supplied to the oil fuel injection valve through the oil supply pipe 11.

  In the diesel engine 6, an oil operation using oil as a fuel and a gas operation using only gas or gas and oil as fuel are performed. When only gas is used as fuel in gas operation, oil may be injected as pilot oil from the oil fuel injection valve described above, or the gas injected from the gas fuel injection valve described above is electrically ignited. May be. For example, the oil operation of the diesel engine 6 is performed in a standby state in which the gas discharged from the compressor 4 becomes the injection pressure Pi to the diesel engine 6 before the gas operation.

  The gas supply system 10 includes a compressor 4, a first supply line 31 that connects the compressor 4 to the tank 2, and a second supply line 32 that connects the compressor 4 to the diesel engine 6. That is, the first supply line 31 guides the gas evaporated from the liquefied gas stored in the tank 2 to the compressor 4, and the second supply line 32 guides the gas compressed by the compressor 4 to the diesel engine 6.

  In the present embodiment, in the first supply line 31, one flow path is divided into two flow paths from the downstream side toward the upstream side. More specifically, the first supply line 31 includes a first branch path 34 for extracting the boil-off gas in the tank 2 and a second branch path provided with a vaporizer 36 for extracting the liquefied gas in the tank 2. 35 and a common path 37 where the first and second branch paths 34 and 35 merge. That is, the first supply line 31 guides the gas vaporized in the tank 2 and the gas forcedly vaporized by the vaporizer 36 to the compressor 4. Although not shown, the first and second branch passages 34 and 35 are each provided with a flow control valve, and the opening degree of these flow control valves is adjusted by the amount of boil-off gas generated in the tank 2. Is done. The first supply line 31 may have only one of the first branch path 34 and the second branch path 35.

  The second supply line 32 is provided with a switching valve 52 and a shut-off valve 53 as a second switching valve is provided downstream of the switching valve 52. The switching valve 52 and the shut-off valve 53 are both on-off valves, and are opened when the diesel engine 6 is in gas operation, and are closed when not in gas operation. The second supply line 32 is connected to a pressure release line 33 for releasing the pressure between the switching valve 52 and the shutoff valve 53 except during gas operation. Further, the second supply line 32 is provided with an accumulator 54 on the downstream side of the shutoff valve 53.

  The compressor 4 sends out the gas so that the gas discharged from the compressor 4 becomes an injection pressure Pi (for example, 15 to 30 MPa in absolute pressure) to the diesel engine 6. Since the injection pressure Pi to the diesel engine 6 is high, the compressor 4 is configured to compress gas with a large compression ratio.

  Specifically, the compressor 4 includes a plurality of compression mechanisms 41 arranged in series, a motor (not shown) that drives these compression mechanisms 41, and a reverse disposed at a discharge port on the downstream side of the compression mechanism 41. A stop valve 44 is included. The compressor 4 also includes a circulation path 42 that circulates the gas to be discharged inside, and an unload valve 43 provided in the circulation path 42. For example, the circulation path 42 is provided so as to bypass the compression mechanism 41 on the most downstream side. The unload valve 43 is a valve (for example, a flow control valve) whose opening degree can be changed based on an electrical signal.

  The ship 1A is also equipped with a gas supply control device 7A (corresponding to the control device of the present invention) and an engine control device 7B. The gas supply control device 7A controls the compressor 4 described above, and the engine control device 7B controls the switching valve 52, the shutoff valve 53, the gas fuel injection valve and the oil fuel injection valve (not shown), and the like. One or both of the gas supply control device 7A and the engine control device 7B are connected to an input device 71 through which various operations are input from the vessel operator. Various operations include selection between oil operation and gas operation, and start of a standby state. Further, the gas supply control device 7A is connected to a pressure gauge 72 that detects the pressure in the upstream portion of the second supply line 32 with respect to the switching valve 52.

  Various signals are transmitted and received between the engine control device 7B and the gas supply control device 7A. For example, in a standby state before the gas operation, a standby signal is transmitted from the gas supply control device 7A to the engine control device 7B. At the start of the gas operation, a signal for starting the gas operation and a signal for the required gas pressure in the gas operation are transmitted from the engine control device 7B to the gas supply control device 7A. Thereafter, when the pressure detected by the pressure gauge 72 reaches the required gas pressure, a gas supply enable signal is transmitted from the gas supply control device 7A to the engine control device 7B.

  The engine control device 7B closes the switching valve 52 and the shutoff valve 53 when the oil operation is selected. In addition, when the gas operation is selected, the engine control device 7B opens the switching valve 52 and the shutoff valve 53 on condition that the gas supply enable signal is received. Thereby, gas operation is started. During the gas operation, the gas supply control device 7A is configured so that the pressure detected by the pressure gauge 72 matches the required gas pressure from the engine control device 8B (that is, the gas pressure corresponding to the load of the diesel engine 6). The rotational speed of the compressor 4 is adjusted.

  Before starting the gas operation, the input device 71 inputs a start of the standby state. For example, the standby state start input is performed before switching from oil operation to gas operation during voyage, or before leaving the port when performing gas operation from the beginning of port departure. When the standby state start is input, the gas supply control device 7A performs a compressor start-up operation for achieving the standby state. In the compressor starting operation, the engine control device 7B keeps the switching valve 52 and the shutoff valve 53 closed.

  Specifically, the gas supply control device 7A first starts the compressor 4 and operates the compressor 4 with the unload valve 43 of the compressor 4 fully opened. Thereafter, when the rotation speed of the compressor 4 reaches a sufficient value, the gas supply control device 7A fully closes the unload valve 43. Thereby, gas is discharged from the discharge port of the compressor 4, and the pressure of the gas in the 2nd supply line 32 rises gradually. Then, the gas supply control device 7A determines that the standby state has been achieved when the gas pressure detected by the pressure gauge 72 has reached the preset injection pressure Pi, and stops the compressor 4. Thereby, the gas of the injection pressure Pi is hold | maintained between the switching valve 52 and the non-return valve 44 of the compressor 4, and a standby state is maintained. For example, the injection pressure Pi is set to be equal to or lower than the lower limit value of the fluctuation range of the required gas pressure during gas operation. Further, when it is determined that the standby state has been achieved, the gas supply control device 7A transmits a standby signal to the engine control device 7B.

  In the standby state, when the pressure detected by the pressure gauge 72 falls below a threshold value α smaller than the injection pressure Pi due to a change in gas temperature in the pipe, the gas supply control device 7A restarts the compressor 4 Then, the pressure of the gas discharged from the compressor 4 is increased again to the injection pressure Pi. For example, the threshold value α may be a value obtained by multiplying the injection pressure Pi by a ratio of 90% or more, or may be a value obtained by subtracting a constant pressure (for example, 1.0 MPa) from the injection pressure Pi. Thereby, the gas discharged from the compressor 4 in the standby state can be maintained in the vicinity of the injection pressure Pi to the diesel engine 6.

  As described above, when the gas operation is selected, the engine control device 7B transmits a gas operation start signal and a signal of a required gas pressure in the gas operation to the gas supply control device 7A. When the gas supply control device 7A receives the gas operation start signal, the gas supply control device 7A restarts the compressor 4 and adjusts the opening degree of the unload valve 43, and the discharge pressure of the compressor 4 (that is, detected by the pressure gauge 72). To match the required gas pressure. When the discharge pressure of the compressor 4 matches the required gas pressure, the gas supply control device 7A transmits a gas supply enable signal to the engine control device 7B. When the engine control device 7B receives a gas supply enable signal, the engine control device 7B opens the switching valve 52 and the shutoff valve 53, and starts supplying fuel gas to the diesel engine 6. Thereafter, as described above, the gas supply control device 7A adjusts the rotational speed of the compressor 4.

  When the gas operation is temporarily switched to the oil operation during the gas operation, the gas supply control device 7A, when the switching valve 52 and the shutoff valve 53 are closed by the engine control device 7B, from the engine control device 7B. The signal may be received, and the compressor 4 may be stopped to maintain the standby state.

  As described above, in the marine vessel 1A of the present embodiment, the compressor 4 cannot perform the back flow of the gas. Therefore, the stop of the compressor 4 causes the injection pressure Pi to flow downstream from the check valve 44 of the compressor 4. Is maintained and the standby state can be maintained. And the power consumption in a standby state can be suppressed by stopping the compressor 4 in a standby state.

  Further, if the oil operation of the diesel engine 6 is performed in the standby state, the oil operation can be quickly switched to the gas operation.

<Modification>
In the embodiment, the gas supply control device 7A stops the compressor 4 when the standby state is achieved. However, when the standby state is achieved, the gas supply control device 7A does not stop the compressor 4, and the unload valve 43 of the compressor 4 is set to be higher than the reference opening for maintaining the injection pressure Pi. You may open to a big opening. This is the same when the operation is temporarily switched to the oil operation during the gas operation.

  Even in this case, gas is no longer discharged from the discharge port of the compressor 4, and the compressor 4 cannot reverse flow of gas, so that the injection pressure is reduced downstream from the check valve 44 of the compressor 4. Retained. Thereby, the standby state can be maintained. Moreover, the load of the compressor 4 falls by making the opening degree of the unload valve 43 larger than a reference opening degree in a standby state. Thereby, power consumption in the standby state can be suppressed. Furthermore, since the compressor 4 is not stopped, the compressor 4 can be started up quickly at the start of gas operation.

  As described above, when the opening degree of the unload valve 43 is set to be larger than the reference opening degree in the standby state, the gas supply control device 7A determines that the pressure detected by the pressure gauge 72 during the standby state is higher than the injection pressure Pi. When the pressure is less than a small threshold value α, the opening of the unload valve 43 is reduced below the reference opening (for example, the unload valve 43 is fully closed), and the pressure of the gas discharged from the compressor 4 is reduced. May be increased again to the injection pressure Pi. Thereby, the gas discharged from the compressor 4 in the standby state can be maintained in the vicinity of the injection pressure Pi to the diesel engine 6.

(Second Embodiment)
Next, with reference to FIG. 2, the ship 1B which concerns on 2nd Embodiment of this invention is demonstrated. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and a duplicate description is omitted.

  In the present embodiment, the holding valve 51 is provided on the upstream side of the switching valve 52 in the second supply line 32. The holding valve 51 holds the gas at the injection pressure Pi between the switching valve 52 in a standby state before the gas operation of the diesel engine 6. In the present embodiment, the holding valve 51 is an on-off valve that is closed in a standby state.

  For example, even when the compressor 4 is stopped in the standby state or when the opening degree of the unload valve 43 is made larger than the reference opening degree in the standby state, the holding valve 51 is normally opened and the standby state is Closed when achieved.

  If the holding valve 51 is provided as in the present embodiment, the gas at the injection pressure Pi can be reliably held at least between the holding valve 43 and the switching valve 52. For this reason, even if there is a slight leak in the check valve 44 of the compressor 4, the gas having the injection pressure Pi can be held on the upstream side of the switching valve 52 for a long time. The holding valve 51 is not necessarily an on-off valve, and may be a check valve as shown in FIG.

(Other embodiments)
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 diesel engine 6 may use only gas as fuel. Furthermore, the diesel engine 6 may be a power generation four-cycle engine instead of the propulsion main engine.

  In the first embodiment, when the compressor 4 is stopped in the standby state, the compressor 4 is provided with a relief valve that can mechanically set the discharge limit pressure instead of the unload valve 43. May be. Alternatively, the compressor 4 that does not include the circulation path 42 and the unload valve 43 can be used.

  The present invention is useful for various ships.

DESCRIPTION OF SYMBOLS 1A, 1B Ship 2 Tank 31 1st supply line 32 2nd supply line 4 Compressor 42 Circulation path 43 Unload valve 51 Holding valve 52 Switching valve 6 Diesel engine 7A Gas supply control apparatus 72 Pressure gauge

Claims (9)

A diesel engine that uses gas as fuel,
A tank for storing liquefied gas;
A compressor connected to the tank via a first supply line and connected to the diesel engine via a second supply line, the compressor compressing the vaporized gas of the liquefied gas;
A switching valve provided in the second supply line that is opened during gas operation of the diesel engine and is closed during other than gas operation;
A control device for stopping the compressor in a standby state in which the gas discharged from the compressor is in a state of being an injection pressure to the diesel engine before the gas operation;
A ship equipped with. A diesel engine that uses gas as fuel,
A tank for storing liquefied gas;
A compressor connected to the tank via a first supply line and connected to the diesel engine via a second supply line, which compresses the gas that the liquefied gas has vaporized, the gas to be discharged A compressor including an internal circulation circuit and an unload valve provided in the circulation path;
A switching valve provided in the second supply line that is opened during gas operation of the diesel engine and is closed during other than gas operation;
Prior to the gas operation, in the standby state where the gas discharged from the compressor becomes the injection pressure to the diesel engine, the unload valve is moved from a reference opening for maintaining the injection pressure. A control device that opens to a large opening,
A ship equipped with.   The holding valve which hold | maintains the gas of the said injection pressure between the said switching valves in the said standby state provided in the upstream part rather than the said switching valves in the said 2nd supply line is provided. The listed ship.   The marine vessel according to claim 3, wherein the holding valve is a check valve.   The ship according to claim 3, wherein the holding valve is an on-off valve that is closed in the standby state. The diesel engine uses gas and oil as fuel,
The ship according to any one of claims 1 to 5, wherein an oil operation of the diesel engine is performed in the standby state. A pressure gauge for detecting a pressure in a portion upstream of the switching valve in the second supply line;
The ship according to claim 1, wherein the control device restarts the compressor when the pressure detected by the pressure gauge falls below a threshold value smaller than the injection pressure during the standby state. A pressure gauge for detecting a pressure in a portion upstream of the switching valve in the second supply line;
The control device reduces the opening of the unload valve to the reference opening or less when the pressure detected by the pressure gauge falls below a threshold value smaller than the injection pressure during the standby state. Item 3. The ship according to item 2.   The ship according to any one of claims 1 to 8, wherein the diesel engine is a two-cycle engine as a main engine for propulsion.

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