JP6504545B2 - Fuel supply apparatus and fuel supply method - Google Patents

Description

  The present invention relates to a fuel supply device and a fuel supply method.

In conventional vessels, a two-stroke cycle, low-speed diesel engine capable of low-speed output and directly driven by a propeller is used.
In recent years, natural gas with low CO ₂ emission has attracted attention as a fuel for low-speed diesel engines. High thermal efficiency and high output can be obtained by injecting and burning high pressure natural gas (fuel gas) such as methane and ethane into the combustion chamber of a low speed diesel engine.

  In some cases, a boil-off gas (hereinafter, referred to as "BOG") in which a part of liquefied natural gas (hereinafter, referred to as "LNG") stored in a tank is vaporized may be used as the natural gas. In this case, specifically, BOG generated in the tank is boosted by a boost pump, and the boosted BOG is injected as a fuel gas into a combustion chamber of the engine (see, for example, Patent Document 1). At this time, the state of the fuel gas supplied to the engine is adjusted to have a predetermined range of pressure and temperature.

For example, a reciprocating compressor may be used as the boost pump. A reciprocating compressor generally comprises a cylinder and a piston for compressing fuel gas introduced into the cylinder, and the fuel gas is supplied to a suction snubber provided on the inlet side of the compression chamber in the cylinder. Then, the fuel gas drawn into the compression chamber and compressed in the compression chamber is discharged to a discharge snubber provided on the outlet side of the compression chamber. The fuel gas in the discharge snubber is supplied to the engine through a pipe (fuel supply pipe) connecting the boost pump and the engine.
In such a booster pump, the suction snubber and the discharge snubber are directly connected by a bypass pipe while being connected through the compression chamber. The bypass pipe is provided with a spillback valve that is configured to open when the pressure of the discharge snubber exceeds a predetermined value, and the spillback valve opens to allow fuel gas to return to the suction snubber through the bypass pipe. The pressure of the discharge snubber is suppressed within a predetermined range.

JP 2012-76561 A

In ships, as in the case of sudden stop of the engine, the supply of fuel gas to the engine may be shut down. The shutdown is performed, for example, by closing a shutoff valve provided in the engine. On the other hand, the pressure of the fuel supply pipe needs to be kept within an allowable range from the viewpoint of the prevention of pipe breakage and the reduction of the economy due to gas discharge for avoiding pipe breakage, and the case where shutdown is performed Even in this case, it is required that the pressure of the fuel supply pipe does not exceed the allowable range. Here, in order to suppress the pressure increase of the fuel supply pipe at the time of shutdown, it is conceivable to open the spill back valve of the pressure rising pump and return the fuel gas in the discharge snubber to the suction snubber. However, since the spillback valve has a low response speed to the control signal instructing to open the spillback valve and opens after the shutoff valve is closed, the pressure of the fuel supply pipe may exceed the allowable range. Therefore, in order to increase the response speed of the spillback valve, for example, it becomes necessary to use an actuator with a higher response speed, which increases the cost.
An object of the present invention is to provide a fuel supply system capable of suppressing the pressure of a fuel supply pipe within an allowable range when the supply of fuel gas to the engine is shut off.

One aspect of the present invention is a fuel supply device for supplying fuel to an engine, wherein
A booster for boosting the pressure of the fuel;
A fuel supply pipe for delivering the fuel from the booster to the engine;
A control unit connected to the engine and controlling an operation of the booster;
The booster is connected to a compression chamber for compressing the fuel, a compression chamber connected to the compression chamber, and a suction chamber to which the fuel introduced by the compression chamber is introduced, and the fuel supply pipe, and the compression chamber A discharge chamber for discharging the fuel, a bypass pipe for communicating the suction chamber with the discharge chamber, and a bypass pipe provided in the middle of the bypass pipe are configured to open when the fuel is returned from the discharge chamber to the suction chamber. A spillback valve, and a check valve having a nonreturn function that prevents the fuel from flowing backward from the compression chamber to the suction chamber,
The control unit controls the spillback valve to open the spillback valve when the fuel supply to the inside of the engine is shut off (when the shutoff valve in the engine is closed), and the spillback valve is controlled. The non-return valve is controlled to release the non-return function of the non-return valve before the back valve is fully opened.

The booster further includes an unloader for keeping the check valve open;
Preferably, the control unit controls the check valve so as to release the non-return function of the check valve by controlling the unloader.

  It is preferable that the fuel supply device further includes a fuel storage container connected to the position of the fuel supply pipe between the booster and the engine and capable of containing the fuel in the fuel supply pipe.

The fuel supply device further includes a control valve that causes the fuel storage container and the fuel supply pipe to communicate with each other.
The control unit may control the control valve such that the fuel supply pipe and the fuel storage container are in communication with each other when the supply of the fuel to the inside of the engine is shut off (for example, at the time of a sudden stop of the engine) .

  Preferably, the control unit controls the check valve so that the nonreturn function of the check valve is restored after the spillback valve is opened.

  The fuel supply device is suitable in the case where the booster continues driving even during the control of the check valve by the control unit and the control of the spillback valve.

In the fuel supply device, when the booster refers to the compression chamber as a first compression chamber,
A first compression device having the first compression chamber, the suction chamber, the discharge chamber, the bypass pipe, the spill back valve, and the check valve;
A second compression device having a second compression chamber for compressing the fuel;
The first compression device is suitable when the fuel pressurized by the second compression device is supplied.

Another aspect of the present invention is a fuel supply method, comprising:
A booster for boosting the pressure of the fuel, a fuel supply pipe for sending the fuel from the booster to the engine, a shutoff valve provided in the fuel supply pipe for shutting off the supply of the fuel to the engine; A fuel supply method for supplying fuel to the engine using a fuel supply apparatus comprising:
The booster is connected to a compression chamber for compressing the fuel, a compression chamber connected to the compression chamber, and a suction chamber to which the fuel introduced by the compression chamber is introduced, and the fuel supply pipe, and the compression chamber A discharge chamber for discharging the fuel, a bypass pipe for communicating the suction chamber with the discharge chamber, and a bypass pipe provided in the middle of the bypass pipe are configured to open when the fuel is returned from the discharge chamber to the suction chamber. A spillback valve, and a check valve having a nonreturn function that prevents the fuel from flowing backward from the compression chamber to the suction chamber,
In the fuel supply method, when the fuel supply to the inside of the engine is shut off,
Opening the spillback valve;
And a step of canceling the check function of the check valve before the spillback valve is fully opened.

  According to the present invention, the pressure of the fuel supply pipe when the supply of fuel gas to the engine is shut off can be suppressed within an allowable range.

It is a figure explaining the composition of the fuel supply system of this embodiment. It is a figure explaining the composition of the booster of a fuel supply system. It is a figure explaining composition of a compressor of a booster. (A) is a figure showing the state in which the non-return function of the non-return valve of a compression device functions, (b) is a figure showing the state in which the non-return function of the non-return valve was cancelled | released. (A) is a figure showing the state controlled so that the nonreturn function of a nonreturn valve functioned by the unloader of a compression device, (b) is controlled so that the nonreturn function of a nonreturn valve may be released by an unloader. It is a figure showing the state which was carried out.

  Hereinafter, the fuel supply device and the fuel supply method of the present invention will be described in detail.

(Fuel supply device)
FIG. 1 shows an outline of a fuel gas supply apparatus (fuel supply apparatus) 1 of the present embodiment.
The fuel gas supply device 1 of the present embodiment is a device that injects BOG generated by the vaporization of liquid fuel into the combustion chamber of the diesel engine 10 at a high pressure as fuel gas and supplies it. The diesel engine 10 of the present embodiment is a diesel engine mounted on a ship, and for example, a low-speed diesel engine with a two-stroke cycle can be used. The rotation speed of the diesel engine 10 is measured by a rotation speed meter (not shown), and feedback control is performed based on the measured rotation speed so as to drive the diesel engine 10 at a desired rotation speed.

  As shown in FIG. 1, the fuel gas supply device 1 includes a fuel tank 15, a booster pump (booster) 3, a fuel gas supply pipe 4, and a fuel gas supply pipe (fuel supply pipe) 5. All of these components of the fuel gas supply system 1 are mounted on a ship.

  The fuel tank 15 stores liquid fuel loaded on a ship as a load. In the fuel tank 15, a part of the liquid fuel is vaporized to spontaneously generate BOG, which is present in the gas phase space above the liquid level of the liquid fuel. As the liquid fuel, liquefied natural gas (LNG), liquefied petroleum gas (LPG) or the like can be used. The fuel tank 15 is connected to the fuel gas supply pipe 4 and supplies the fuel gas to the pressure rising pump 3 via the fuel gas supply pipe 4.

  The inlet side of the fuel gas is connected to the fuel gas supply pipe 4, and the outlet side of the fuel gas is connected to the fuel gas supply pipe 5. The boost pump 3 boosts the fuel gas supplied through the fuel gas supply pipe 4 and supplies the boosted fuel gas to the diesel engine 10 through the fuel gas supply pipe 5. As the pressure rising pump 3, a reciprocating motion compressor of a type in which a movable portion such as a piston reciprocates can be used. The boost pump 3 is controlled by the control unit 9 and driven. The details of the booster pump 3 will be described later.

One end of the fuel gas supply pipe 5 is connected to the booster pump 3 and the other end is connected to the combustion chamber of the diesel engine 10. The fuel gas is pressure-regulated to a predetermined pressure (for example, 150 to 300 bar) by the pressure rising pump 3 and then supplied to the combustion chamber of the diesel engine 10 via the fuel gas supply pipe 5.
Further, a pressure gauge (not shown) is provided near the inlet of the diesel engine 10 in the fuel gas supply pipe 5 and measures the pressure of the fuel gas in the fuel gas supply pipe 5 as the pressure of the fuel gas supply pipe 5 be able to.

  The control unit 9 is connected to the boost pump 3 and the like, and controls the operation of each of these units. The control unit 9 also receives a required fuel pressure and a gas load output from the diesel engine 10. The required fuel pressure is the pressure of the fuel gas that the diesel engine 10 requires from the outside according to the size of the output of the diesel engine 10, and the gas load is based on the gas fuel when the engine output rated value is 100%. It shows the rate of load. When the required fuel pressure falls below a predetermined value, or when the engine is stopped, the diesel engine 10 shuts down and closes a shutoff valve (not shown) in the diesel engine 10. When the shutoff valve is closed, the diesel engine 10 outputs a shutdown signal to notify the outside that the shutoff valve is closed. The shutdown signal is a signal of 0 bar fuel demand pressure and 0% gas load. The shutoff valve is provided in the diesel engine 10, and is a valve for shutting off the supply of fuel gas to a portion (inside the diesel engine 10) of the diesel engine 10 downstream of the shutoff valve. The shutoff valve is provided at a position adjacent to the portion of the diesel engine 10 connected to the fuel gas supply pipe 5 (near the inlet of the diesel engine 10).

(Boost pump)
Next, the booster pump 3 will be described in detail with reference to FIGS.
Here, a case where a reciprocating compressor including a plurality of compression devices 20, 30a, 30b, 30c, and 30d shown in FIG. 2 is used as the pressure rising pump 3 will be described as an example. FIG. 2 is a diagram schematically illustrating the configuration of the pressure rising pump 3. Although the number (stage number) of the compression devices included in the pressure rising pump 3 is five in FIG. 2, it may be any one of one to four, or six or more. The compression devices 20, 30a to 30d are connected in series in the direction in which the fuel gas is supplied, and are driven by a crankshaft 38 driven by a motor 32. The drive of the motor 32 is controlled by the controller 9. The fuel gas supplied through the fuel gas supply pipe 4 passes through the second to fourth stage compressors 30c, 30b and 30a in order from the first stage compressor 30d arranged closest to the inlet. Then, the pressure is supplied to the fifth stage (final stage) compressor 20 disposed closest to the outlet side, and boosted stepwise. For example, the compression devices 20, 30a to 30d are configured to compress the fuel gas at substantially the same compression rate, and when the compression rate of each stage is 3.1 times, the pressure of the fuel gas is from atmospheric pressure to 300 bar. It can be boosted to a certain degree of pressure. The compression devices 20, 30a to 30d are configured in substantially the same manner except for the internal volume and the like of a cylinder to be described later, and the compression device 20 will be described as a representative below.

  As shown in FIG. 3, the compression device 20 has a cylinder 21 and a piston 34 connected to a crankshaft 38. FIG. 3 is a diagram schematically illustrating the configuration of the compression device 20. As shown in FIG. Inside the cylinder 21, a compression chamber 21a (first compression chamber) for compressing the fuel gas is formed. In addition to the compression chamber 21a, the compression device 20 has a suction snubber (suction chamber) 23, a discharge snubber (discharge chamber) 25, a bypass pipe 27, a spill back valve 29, and check valves 22 and 24. . Note that these components of the compression device 20 are also included in the compression devices 30a to 30d.

  The suction snubber 23 is connected at the inlet side to the discharge snubber (not shown) of the fourth stage compressor 30 a and at the outlet side to the compression chamber 21 a (first compression chamber). The fuel gas supplied to the suction snubber 23 passes through the check valve 22 and is supplied to the compression chamber 21a as the piston 34 moves so as to expand the volume of the compression chamber 21a. The check valve 22 allows the flow of fuel gas from the suction snubber 23 to the compression chamber 21a except when the shutdown is performed or when the boost pump 3 is started (hereinafter referred to as the shutdown time etc.), and the compression chamber It has a non-return function which prevents the fuel gas in 21 a from flowing back to the suction snubber 23. When the pressure rising pump 3 is started, the non-return function of the check valve 22 is released to reduce the torque. In the present specification, the function of the non-return function means that the effect of preventing back flow is exhibited. Further, that the non-return function is released means that the effect of preventing the back flow is not exhibited, that is, the back flow can not be prevented.

Here, the structure of the check valve 22 will be described with reference to FIG. Fig.4 (a) is a figure showing the state which the non-return valve 22 closed, and FIG.4 (b) is a figure showing the state which the non-return valve 22 opened. The check valve 22 is closed as shown in FIG. 4 (a) except at the time of shutdown etc., and controlled at the time of shutdown etc. as shown in FIG. 4 (b).
The check valve 22 includes a valve seat 51, a valve seat 59, and a plurality of valve plates 53, 55, and 57 disposed between the valve seat 51 and the valve seat 59. The valve seat 51 is a compression chamber. The valve receiver 59 is disposed on the side of the suction snubber 23. The valve seat 51, the valve plates 53 to 57, and the valve receiver 59 are all disk-shaped members. A shaft 52 extending toward the valve receiver 59 is provided at the center of the valve seat 51, and the shaft 52 is disposed so as to pass through the valve plates 53 to 57 and the valve receiver 59. The check valve 22 further includes a biasing member (not shown) such as a coil spring, and the valve seat 51 is in a state where no external force is acting on the check valve 22 (for example, an unloading state described later). , The valve plates 53 to 57, and the valve receiver 59 are spaced apart from one another. A plurality of recesses 51a serving as fuel gas passages are formed in the region of the valve seat 51 on the outer circumferential side of the shaft 52, and a plurality of valve plates 53 to 57 and valve bearings 59 serve as fuel gas passages. The concave portions 53a, 55a, 57a, 59a are formed. The recesses 53a, 55a, 57a, 59a are integrated in the extending direction of the shaft 52 in a state in which the valve plates 53 to 57 and the valve receiver 59 are in contact with each other as shown in FIG. 4A. The integral space is closed by a valve seat 51. Therefore, when the check valve 22 is closed, fuel gas can not flow from the compression chamber 21a to the suction snubber 23, as shown by the broken arrow in FIG. 4A, and reverse flow is prevented. . On the other hand, when the check valve 22 is open, fuel gas can flow from the compression chamber 21a to the suction snubber 23, for example, along the broken arrow in FIG. 4 (b).
The structure of the check valve 22 is not limited to the one described above. For example, in the example shown in FIG. 4, a plurality of concave portions 51a to 59a are respectively provided at a plurality of radial positions of valve seat 51, valve plates 53 to 57, and valve In addition to this form, the recesses 51a to 59a have a plurality of straight lines extending radially outward from the center of each of the valve seat 51, the valve plates 53 to 57, and the valve receiver 59. It may be shaped like a circle, and may have a plurality of dispersed dots formed.

  Returning to FIG. 3, the discharge snubber 25 is connected at the inlet side to the compression chamber 21 a and at the outlet side to the fuel gas supply pipe 5. The fuel gas in the compression chamber 21a is supplied to the discharge snubber 25 through the check valve 24 as the piston 34 moves so as to reduce the volume of the compression chamber 21a. The check valve 24 allows the flow of the fuel gas from the compression chamber 21a to the discharge snubber 25 while preventing the fuel gas in the discharge snubber 25 from flowing back to the compression chamber 21a. The check valve 24 may also be configured substantially the same as the check valve 22. The valve seat of the check valve 24 is disposed on the compression chamber 21a side, and the valve receiver is disposed on the discharge snubber 25 side. Ru. Unlike the check valve 22, the check valve 24 is not controlled to open at the time of shutdown or the like.

  The bypass pipe 27 is a pipe that connects the suction snubber 23 and the discharge snubber 25 without passing through the compression chamber 21 a. The spillback valve 29 is a control valve provided in the middle of the bypass pipe 27 and controlled by the control unit 9. The spillback valve 29 is configured to open when the pressure of the fuel gas supply pipe 5 exceeds a predetermined value, and in the open state, the fuel gas can be returned from the discharge snubber 25 to the suction snubber 23. Specifically, the spill back valve 29 is driven to open by being driven by an actuator (not shown) controlled by the control unit 9, and after the control unit 9 outputs a control signal instructing to open, predetermined Fully open (completely open) after a lapse of time (eg 12 seconds). To fully open means that the opening degree of the valve exceeds 80%, and preferably means that the opening degree is 100%. The degree of opening is the cross-sectional area of the portion through which fluid flows when the valve is open, taking up the cross-sectional area of the entire flow path. The predetermined value of the pressure of the fuel gas supply pipe 5 is, for example, 300 bar when the upper limit value of the allowable range is 315 bar.

Shutdown shuts off a shutoff valve (not shown) in the diesel engine 10. The shutdown may be, for example, stopping the operation of the diesel engine 10 in order to reduce the speed of the ship by entering the port, or to supply the fuel supplied to the diesel engine 10 to increase the speed in the open sea etc from the fuel gas It is performed when switching to fuel (for example, heavy oil). When the shutdown signal output from the diesel engine 10 is input, the control unit 9 outputs a control signal instructing to open the spill back valve 29 and instructs to cancel the non-return function of the check valve 22. Output control signal. The spillback valve 29 starts an opening operation after the shutdown signal is output. On the other hand, the check valve 22 starts opening operation, for example, 3 seconds after the shutdown signal is output, and opens after, for example, 5.5 seconds after the shutdown signal is output, and the non-return function is released.
As described above, in the present embodiment, the amount of fuel gas in the discharge snubber 25 returning to the suction snubber 23 in the compression device 20 at the final stage of the pressure rising pump 3 does not have a sufficient degree of opening of the spillback valve 29 at shutdown. Because of this, the non-return function of the non-return valve 22 is released when it is small. Therefore, in the compression device 20, the fuel gas in the compression chamber 21a can be returned to the suction snubber 23, and the fuel gas is supplied to the compression chamber 21a as the piston 34 continues to reciprocate. Returning to the snubber 23 is repeated. As a result, the speed at which the fuel gas is supplied from the discharge snubber 25 to the fuel gas supply pipe 5 is reduced, the pressure rise of the fuel gas supply pipe 5 is mitigated, and the pressure of the fuel gas supply pipe 5 is suppressed to an allowable range. it can. The allowable range is a pressure range equal to or less than the opening pressure value of the safety valve provided in the fuel supply pipe. The allowable range of the pressure of the fuel gas supply pipe 5 is, for example, a predetermined ratio (for example, 5%) to the upper limit when the upper limit of the range of the pressure of the fuel gas adjusted by the pressure rising pump 3 is 300 bar. It refers to the range below the multiplied value (for example, 315 bar or less).

  In the present embodiment, the compressor 20 of the booster pump 3 further includes an unloader 41 (see FIG. 5) for maintaining the check valve 22 in the open state, and the control unit 9 controls the unloader 41. Preferably, the check valve 22 is controlled such that the non-return function of the check valve 22 is released. The unloader 41 controls the non-return valve 22 so that the non-return function of the non-return valve 22 functions during normal operation (except during shutdown) of the diesel engine 10, and during reverse operation, etc. The check valve 22 is controlled so that the non-return function of the valve 22 is released. Thus, the unloader 41 brings the suction snubber 23 into communication with the compression chamber 21a by releasing the non-return function of the check valve 22, and brings the compression chamber 21a into an unloading state where the fuel gas is not boosted. . For example, an air driven valve driven by air pressure is used as the unloader 41, but a valve driven by oil pressure, water pressure or the like may be used, or a manual valve may be used.

Here, control of the check valve 22 by the unloader 41 will be described with reference to FIG. FIG. 5A is a diagram showing a state in which the reverse function of the check valve 22 is controlled to function by the unloader 41, and the unloader 41 is controlled to release the reverse function of the check valve 22. FIG. In addition, in FIG. 5 (a) and FIG.5 (b), the hole of 51a-59a is abbreviate | omitted for the facilities of description.
Specifically, the unloader 41 has a casing 61, a diaphragm 63 movable in the casing 61, a rod 65 connected to the diaphragm 63, and an air pressure supply device (not shown) for supplying air pressure to the casing 61. doing. The diaphragm 63 is biased within the casing 61 by a biasing member (not shown) to project the rod 65 (projecting downward in FIG. 5). The tip of the rod 65 (the lower end in FIG. 5) is in contact with a member 67 attached to the valve seat 51 of the check valve 22, and the rod 65 projects to provide a pressure contact force via the members 67 and 68. It acts on the check valve 22. The members 67 and 68 are members for transmitting the pressure contact force from the rod 65 to a wider area of the valve seat 51.

In the unloader 41 thus configured, the diaphragm 63 closes the check valve 22 by causing the rod 65 to project as shown in FIG. 5A during normal operation of the diesel engine 10 Keep the That is, the non-return function of the check valve 22 is made to function. On the other hand, at the time of shutdown, etc., the air pressure supply device is activated in response to the control signal from the control unit 9, and air is in the space between the inner wall of the casing 61 and the diaphragm 63 (the space indicated by reference numeral 61a in FIG. 5). As supplied, the diaphragm 63 moves upward in FIG. 5 in the casing 61, thereby retracting the rod 65 as shown in FIG. 5 (b). As a result, the check valve 22 is released from the pressure contact force of the rod 65, and the non-return function is released by opening. As a result, the fuel gas in the compression chamber 21 a of the pressure rising pump 3 is not in the pressure rising state. After the control unit 9 outputs a control signal to the unloader 41 so that the check function of the check valve 22 is released, the control unit 9 opens the spill back valve 29 for a period of time until the unload state is entered. It is shorter than the time from the output of the control signal indicating that the spill back valve 29 completes the opening operation. That is, the unloader 41 has a higher response speed than the spillback valve 29. For this reason, even after the shutdown, before the operation of opening the spillback valve 29 starts, the speed at which the fuel gas is supplied to the fuel gas supply pipe 5 is reduced, and the pressure rise of the fuel gas supply pipe 5 is mitigated. The pressure of the fuel gas supply pipe 5 can be suppressed within an allowable range.
When the compressor 20 does not have the unloader 41, for example, as the check valve 22, the response speed is larger than that of the spill back valve 29, and the control valve 9 is directly controlled by the control unit 9 (for example, hydraulic suction type Control valve) may be used. Further, in the present specification, the case where the check valve is controlled includes the case where the check valve is directly controlled as well as the case where the check valve is controlled using, for example, the above-described unloader.

Fuel gas supply device 1 is further connected to the position of fuel gas supply pipe 5 between boost pump 3 and diesel engine 10, as shown in FIG. It is preferable to provide the following volume tanks (fuel storage containers) 11 and 12. By connecting the volume tanks 11 and 12 to the fuel gas supply pipe 5, an internal space larger than the internal volume of the fuel gas supply pipe 5 is formed, and the shutoff valve in the diesel engine 10 is closed upon receiving a shutdown signal. In this case, the speed at which the pressure of the fuel gas supply pipe 5 rises is reduced. The number of volume tanks is not limited to two, and may be one or three or more. When the number of volume tanks is more than one, the volumes may be equal or different. Also, the volume of the volume tank may be constant or variable.
By providing the volume tanks 11 and 12 in this manner, the speed at which the pressure of the fuel gas supply pipe 5 increases is reduced, and the check valve described above is released so that the non-return function of the check valve 22 is released. The pressure of the fuel gas supply pipe 5 can be more reliably suppressed to an acceptable range by a synergetic effect with the effect of reducing the speed at which the fuel gas is supplied to the fuel gas supply pipe 5 obtained by controlling 22. it can.

  When the fuel gas supply device 1 includes the volume tanks 11 and 12, the fuel gas supply device 1 may further include a control valve (not shown) that causes the volume tanks 11 and 12 and the fuel gas supply pipe 5 to communicate with each other. Specifically, the control valve receives a control signal output from the control unit 9 in response to the shutdown signal from the diesel engine 10 being input to the control unit 9, and the fuel gas supply pipe 5 and the volume tank 11 , 12 communicate with each other. The fuel gas supply pipe 5 and the volume tanks 11, 12 communicate with each other at the same time or after the start of the operation of opening the spillback valve 29. As a result, the fuel gas in the fuel gas supply pipe 5 moves to the volume tanks 11, 12, and the pressure of the fuel gas supply pipe 5 can be suppressed within the allowable range. During normal operation of the diesel engine 10, fuel gas is not supplied into the volume tanks 11, 12.

Preferably, the control unit 9 controls the check valve 22 so that the nonreturn function of the check valve 22 is restored after the spill back valve 29 is opened. After shutdown, even after the shutoff valve in the diesel engine 10 is closed, the fuel gas in the discharge snubber 25 returns to the suction snubber 23 through the bypass pipe 27 if the spillback valve 29 is opened be able to. For this reason, even if the check valve 22 is closed and the fuel gas can not return from the compression chamber 21a to the suction snubber 23, the speed at which the fuel gas is supplied to the fuel gas supply pipe 5 is small. The pressure of 5 is reduced to an acceptable range.
In addition, when an unloading state occurs in any of the compression devices, the pressure of the fuel gas in the pressure boosting pump 3 decreases, but the pressure of the fuel gas once decreased is once again boosted to a desired pressure. Takes some time, and the supply of fuel gas to the diesel engine 10 is delayed accordingly. Therefore, it is preferable to control the check valve 22 so that the check valve 22 is closed after the spill back valve 29 is opened after the shutdown. Control for closing the check valve 22 can be performed, for example, by outputting a control signal for stopping supply of air pressure into the casing 61 and driving the unloader 41 so that the check valve 22 is closed. The control for closing the check valve 22 is preferably performed after the spillback valve 29 is completely open. This is because the larger the opening degree of the spillback valve 29, the smaller the differential pressure between the outlet side and the inlet side of the compression chamber 21a, which is preferable.

  In the case where the fuel gas supply device 1 continues driving even during the period in which the control unit 9 controls the check valve 22 and the spillback valve 29, the fuel gas supply device 1 ie, the driving of the booster pump 3 It can be suitably used when it is maintained even after the shutoff valve is closed. Once the driving of the pressure rising pump 3 is stopped, the pressure in the pressure rising pump 3 is lowered, and it takes some time to pressure the fuel gas again. In particular, in the case where the booster pump 3 is a multistage reciprocating compressor, for example, in the case where the amount of supply of fuel gas is reduced (throttled), all compression is generally performed in order to suppress pressure rise in the booster pump In order to boost the fuel gas from atmospheric pressure to the desired pressure, the system is opened by opening the spillback valve of the device and returning the fuel gas in the discharge snubber to the most intake suction snubber (whole spillback). The time required will be long. Therefore, from the viewpoint of smoothly supplying the fuel gas to the diesel engine 10, it is preferable to stop the driving of the pressure rising pump 3 as much as possible. In the present embodiment, as described above, after the shutdown, the check valve 22 is controlled so that the non-return function of the check valve 22 is released before the spill back valve reaches the full opening. Therefore, even when fuel gas is supplied again to the diesel engine 10 immediately after shutdown, for example, the pressure of the fuel gas supply pipe 5 can be suppressed within an allowable range while maintaining the driving of the pressure rising pump 3.

  According to the present embodiment, when the shutoff valve in the diesel engine 10 is closed, the spillback valve 29 starts to open and before the spillback valve 29 is fully opened, the nonreturn function of the check valve 22 has Since the check valve 22 is controlled to be released, the speed at which the fuel gas is supplied to the fuel gas supply pipe 5 is reduced, and the pressure rise of the fuel gas supply pipe 5 is mitigated. Pressure can be reduced to an acceptable range.

In the present embodiment, when the booster pump 3 is a multistage reciprocating compressor, unloading may be performed only by the last stage compression device 20, and a plurality of compression devices including the last stage compression device 20 may be used. You may unload it. Also, although the above-described compression device is an example of a single-acting type that compresses the fuel gas only on one side of the direction of movement of the piston (the space above the piston in FIG. 3), both sides of the direction of movement of the piston May be a double acting type that compresses the fuel gas. When the compressor is a double acting type, suction snubber, discharge snubber, check valve, bypass pipe, spill back valve, and unloader are provided on both sides of the piston and control one or both of the unloader to unload. It can be performed.
The diesel engine 10 to which the fuel gas is supplied by the fuel gas supply device 1 may be a gas-fired diesel engine using only the fuel gas as fuel, or may be fueled with heavy oil. It may be a switchable diesel engine. Further, the engine to which the fuel gas is supplied by the fuel gas supply device 1 may be an engine other than a diesel engine (for example, a reciprocating engine).

(Fuel supply method)
Next, the fuel supply method of the present embodiment will be described.
According to the fuel supply method of the present embodiment, the fuel gas can be supplied to the diesel engine 10 using the fuel gas supply device 1 described above. The fuel supply method includes a step of opening the spill back valve 29 (ST10) and a step of releasing the non-return function of the check valve 22 before the spill back valve 29 is fully opened (ST20). Do.

Specifically, in the step of opening the spillback valve 29 (ST10), a control signal instructing the closing of the spillback valve 29 is output from the controller 9 to the spillback valve 29, and the spillback valve 29 is opened.
Specifically, in the step (ST20) of canceling the non-return function of the check valve 22, the control unit 9 instructs a control signal to cancel the non-return function of the check valve 22, For example, the check valve 22 is output to the unloader 41 to open the check valve 22.
Control signals output from the control unit 9 to the spillback valve 29 and the unloader 41 are output simultaneously with the input of the shutdown signal to the control unit 9.

For example, in the fuel supply method of the present embodiment, when the supply of fuel gas to the inside of the diesel engine 10 is shut down (shutdown), about 3 seconds after shutdown, the unloader 41 starts driving and the check valve 22 The check valve 22 is completely opened to complete the unloading state after about 2.5 seconds have elapsed (about 5.5 seconds after shutdown). Therefore, the fuel gas in the compression chamber 21a can be returned to the suction snubber 23 even before the spillback valve 29 reaches full opening. The spillback valve 29 starts an opening operation before the check valve 22 starts to open, and is fully opened after the unloading state is completed. Further, the check valve 22 is controlled to be closed by the unloader 41 after the unload state lasts for about several seconds to about 10 seconds, and the boost pump 3 is loaded, but at this time, the boost pump 3 is driven. Even when maintained, the fuel gas of the discharge snubber 25 can return to the suction snubber 23 through the bypass pipe 27.
According to the fuel supply method of the present embodiment, when the shutoff valve in the diesel engine 10 is closed, the nonreturn function of the check valve 22 is canceled before the spillback valve 29 is fully opened. Because the speed at which the fuel gas is supplied to the fuel gas supply pipe 5 is reduced and the pressure rise of the fuel gas supply pipe 5 is mitigated, the pressure of the fuel gas supply pipe 5 is suppressed to an allowable range. Can.

(Experimental example)
In order to confirm the effect of the present invention, when the check valve 22 is opened (when unloading is performed) by the unloader 41 or when it is not opened (unloading) using the fuel gas supply device 1 described above The pressure change of the fuel gas supply pipe 5 after shutdown was measured in the four cases obtained by combining the case where the loading was not performed, the case where the volume tank was or was not provided, and the case where the volume tank was not provided. A five-stage reciprocating compressor was used as the booster pump 3. For the volumetric tank, one container of CNG fuel having an inner volume of 1 m ³ used for filling compressed natural gas (CNG) was used. The target value of the pressure of the fuel gas supplied to the diesel engine 10 was 30 MPa. The shutdown was performed by stepping the output (load) of the diesel engine 10 from 20,000 kW to 0 kW. Unloading after shutdown was performed using the final stage compressor 20. Three seconds after the load of the diesel engine 10 dropped to 0 kW, the unloader 41 started to open the check valve 22 and after 2.5 seconds, the check valve 22 was completely opened to complete the unloading state. The pressure of the fuel gas supply pipe 5 was measured using a pressure gauge provided in the middle of the fuel gas supply pipe 5. The case where the pressure of the fuel gas supply pipe 5 is 31.5 MPa or less is taken as the allowable range.

As a result, when the volume tank was not provided, the pressure of the fuel gas supply pipe 5 increased to 32.33 Mpa when unloading was performed, whereas it increased to 30.98 MPa when unloading was not performed. . From this, it was found that the pressure of the fuel gas supply pipe 5 can be suppressed within the allowable range (31.5 MPa or less) by performing unloading compared to the case where unloading is not performed.
In addition, when the volume tank was provided, the pressure of the fuel gas supply pipe 5 increased to 31.91 MPa when unloading was performed, but increased to 30.25 MPa when unloading was performed. Also from this fact, it was found that the pressure of the fuel gas supply pipe 5 can be suppressed within the allowable range by performing unloading as compared with the case where unloading is not performed. Moreover, it has been found that the effect of suppressing the pressure rise of the fuel gas supply pipe 5 is greater when the volume tank is provided as compared with the case where the volume tank is not provided.

  As mentioned above, although the fuel supply apparatus and fuel supply method of the present invention were explained in detail, the present invention is not limited to the above-mentioned embodiment and example, and performs various improvement and change in the range which does not deviate from the main point of the present invention. Of course it is good.

1 Fuel gas supply system (fuel supply system)
3 Booster 5 Fuel gas supply pipe (fuel supply pipe)
7 Pressure regulating valve (shutdown valve)
9 control unit 10 diesel engine 11, 12 tank (fuel storage container)
20 first compression device 21 first compression chamber 22 check valve 23 suction snubber (suction chamber)
25 Discharge snubber (discharge chamber)
27 bypass pipe 29 spill back valve 30a, 30b, 30c, 30d second compression device 31 second compression chamber 41 unloader

Claims (8)

A fuel supply device for supplying fuel to an engine;
A booster for boosting the pressure of the fuel;
A fuel supply pipe for delivering the fuel from the booster to the engine;
A control unit connected to the engine and controlling an operation of the booster;
The booster is connected to a compression chamber for compressing the fuel, a compression chamber connected to the compression chamber, and a suction chamber to which the fuel introduced by the compression chamber is introduced, and the fuel supply pipe, and the compression chamber A discharge chamber for discharging the fuel, a bypass pipe for communicating the suction chamber with the discharge chamber, and a bypass pipe provided in the middle of the bypass pipe are configured to open when the fuel is returned from the discharge chamber to the suction chamber. A spillback valve, and a check valve having a nonreturn function that prevents the fuel from flowing backward from the compression chamber to the suction chamber,
The control unit controls the spillback valve so that the spillback valve is opened when the fuel supply to the inside of the engine is shut off, and the control unit controls the check valve before the spillback valve is fully opened. A fuel supply device characterized in that the check valve is controlled so that the non-return function is released. The booster further includes an unloader for keeping the check valve open;
The fuel supply device according to claim 1, wherein the control unit controls the check valve to release the non-return function of the check valve by controlling the unloader.   The fuel supply device according to claim 1, further comprising a fuel storage container connected to the position of the fuel supply pipe between the booster and the engine and capable of containing the fuel in the fuel supply pipe. . The fuel cell system further includes a control valve that causes the fuel container and the fuel supply pipe to communicate with each other.
The fuel supply apparatus according to claim 3, wherein the control unit controls the control valve such that the fuel supply pipe and the fuel storage container communicate with each other when the supply of the fuel into the engine is shut off. .   The fuel supply according to any one of claims 1 to 4, wherein the control unit controls the check valve so that the nonreturn function of the check valve is restored after the spillback valve is opened. apparatus.   The fuel supply device according to any one of claims 1 to 5, wherein the booster continues driving during control of the check valve by the control unit and control of the spill back valve. The booster is
When the compression chamber is referred to as a first compression chamber,
A first compression device having the first compression chamber, the suction chamber, the discharge chamber, the bypass pipe, the spill back valve, and the check valve;
A second compression device having a second compression chamber for compressing the fuel;
The fuel supply device according to any one of claims 1 to 6, wherein the fuel pressurized by the second compression device is supplied to the first compression device. A fuel supply method for supplying fuel to an engine by using a fuel supply device comprising: a booster for boosting the pressure of fuel; and a fuel supply pipe for sending the fuel from the booster to the engine,
The booster is connected to a compression chamber for compressing the fuel, a compression chamber connected to the compression chamber, and a suction chamber to which the fuel introduced by the compression chamber is introduced, and the fuel supply pipe, and the compression chamber A discharge chamber for discharging the fuel, a bypass pipe for communicating the suction chamber with the discharge chamber, and a bypass pipe provided in the middle of the bypass pipe are configured to open when the fuel is returned from the discharge chamber to the suction chamber. A spillback valve, and a check valve having a nonreturn function that prevents the fuel from flowing backward from the compression chamber to the suction chamber,
In the fuel supply method, when the fuel supply to the inside of the engine is shut off,
Opening the spillback valve;
Allowing the nonreturn function of the check valve to be released before the spillback valve is fully opened.

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