JP2018173025A - Fuel gas supply system, ship, and fuel gas supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply stable fuel by controlling the supply of the fuel so as to cope with a rapid load change of an engine even if the load change of the engine occurs.SOLUTION: A fuel gas supply system 10 for supplying fuel gas to an engine 40 comprises a tank 20 for liquefied gas, a pressurizing mechanism 30 for pressurizing and delivering boil-off gas of the liquefied gas or the liquefied gas as fuel, and a pressurization control device 62 for controlling a delivery rate of the fuel to be delivered by the pressurizing mechanism. The control of the delivery rate to be performed by the pressurization control device includes feedback control for controlling the delivery rate on the basis of a difference between a set pressure established on the basis of a required pressure of the fuel required by the engine and a measured pressure of the fuel after the pressurization, and feedforward control for controlling the delivery rate on the basis of a change in a gas load signal indicating consumption of the fuel gas in the engine.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel gas supply system that supplies a boil-off gas vaporized from a liquefied gas to an engine as a fuel gas, a ship using the system, and a fuel gas supply method.

  In an LNG (liquefied natural gas) carrier, boil-off gas is vaporized from the liquefied gas stored in the tank. In order to process this boil-off gas effectively, it is performed as fuel gas to a ship engine.

A low-pressure fluid such as boil-off gas needs to be a high-pressure fluid in order to be adapted as an engine fuel gas. For this reason, in a fuel gas supply system that supplies boil-off gas as fuel gas for an engine, fuel such as boil-off gas is pressurized (compressed) using, for example, a multistage pressurization device. This pressurized fuel is delivered to the engine.
On the other hand, the demand for fuel gas in an engine may change due to load fluctuations. In this case, it is desired to control the amount of fuel delivered by the fuel gas supply system in response to engine load fluctuations.

For example, there is known a ship that can supply fuel gas having different pressures to two or more gas-fired diesel engines and can save space (Patent Document 1).
In the ship, the fluctuation of the supply gas pressure can be suppressed to an allowable range by controlling the rotation speed of the high-pressure pump that is a pressurizing device, the opening degree of the flow control flight, and the pressure regulating valve.

JP2015-49881A

However, in the above-described ship, when the load of a part of engines among a plurality of operating engines changes suddenly, for example, another engine enters a state of preparation for operation while part of the engine is operating, and this engine upstream When the flow control valve of the engine is opened, a large amount of fuel gas flows into the engine, and as a result, the pressure of the fuel gas in the pipe suddenly decreases, and the fuel gas supplied to some of the operating engines There is a problem that the pressure of the pressure is significantly lower than the required pressure. Further, when some of the engines are stopped due to a trouble during operation of the plurality of engines, there is a possibility that the pressure of the fuel gas in the pipe rapidly rises due to a sudden decrease in the fuel gas consumption.
Such a problem is not limited to a plurality of engines, and may occur even when the load suddenly changes in one engine. As described above, it is difficult to change the supply amount of the fuel gas supplied from the fuel gas supply system in response to a rapid load fluctuation of the engine. Moreover, in the said ship, it is not disclosed how to control the supply amount of fuel gas.

  Accordingly, the present invention provides a fuel gas that can supply a stable fuel gas to the engine by controlling the supply of the fuel gas so as to cope with the engine load fluctuation, even if a sudden engine load fluctuation occurs. It aims at providing a supply system, a fuel gas supply method, and a ship.

One embodiment of the present invention is a fuel gas supply system that supplies fuel gas to an engine. The fuel gas supply system is
A tank for storing liquefied gas;
A pressurizing mechanism that pressurizes and sends out the boil-off gas vaporized from the liquefied gas or the liquefied gas as fuel in order to supply the boil-off gas vaporized from the liquefied gas as a fuel gas to the engine;
A pressurization control device that controls the amount of fuel delivered by the pressurization mechanism;
And a main pipe that connects the pressurizing mechanism and the engine and through which the fuel delivered by the pressurizing mechanism flows to the engine.
The control of the delivery amount performed by the pressurization control device is performed by adjusting the delivery amount based on a difference between a set pressure determined based on a required fuel pressure required by the engine and a measured pressure of the fuel in the main pipe. Feedback control to be controlled, and feedforward control to control the delivery amount based on a change in a gas load signal indicating a fuel gas consumption amount of the engine.

The main pipe is provided with an open / close valve for turning on / off the supply of fuel gas to the engine,
The control of the delivery amount performed by the pressurization control device further includes feedforward control for controlling the delivery amount based on information on a change from on to off or from off to on of the opening / closing valve. preferable.

  It is preferable that the pressurization control device controls the delivery amount so that the control amount of the delivery amount is adjusted according to the set pressure.

The pressurizing mechanism includes a pressurizer that pressurizes the fuel, a bypass pipe that bypasses the pressurizer and connects a pipe through which fuel flows before and after pressurization by the pressurizer, and the bypass pipe An adjustment valve that controls the amount of fuel flowing through
It is preferable that the pressurization control device controls the delivery amount by controlling the opening degree of the adjustment valve using the feedforward control.

The pressurizing mechanism includes a pressurizer that pressurizes the fuel, a bypass pipe that bypasses the pressurizer and connects a pipe through which fuel flows before and after pressurization by the pressurizer, and the bypass pipe A multistage pressurizing mechanism provided in series with a plurality of sets each including an adjustment valve that controls the amount of fuel flowing through
It is preferable that the pressurization control device controls the delivery amount by controlling the opening degree of each of the plurality of sets of adjusting valves using the feedforward control.

Another aspect of the present invention is:
The fuel gas supply system;
A propulsion engine driven using fuel pressurized by the pressurizing mechanism;
And a control unit for controlling the propulsion engine.

Another aspect of the present invention is a fuel gas supply method for supplying fuel gas to an engine. The fuel gas supply method is
In order to supply the boil-off gas vaporized from the tank storing the liquefied gas as a fuel gas to a plurality of engines, pressurizing and sending the boil-off gas vaporized from the liquefied gas or the liquefied gas as fuel; and
Feedback control of the delivery amount based on a difference between a set pressure determined based on a required fuel pressure required by the engine and a measured pressure of the pressurized fuel;
Feedforward-controlling the delivery amount based on fluctuations in a gas load signal indicating fuel gas consumption of the engine.
The feedforward control is performed when the fluctuation of the gas load signal is out of a predetermined range.

  And a feedforward control for controlling the delivery amount based on a change from on to off or off to on of an on-off valve for turning on / off the supply of fuel gas to each engine. preferable.

  In the control of the delivery amount, it is preferable that the control amount of the delivery amount is adjusted according to the set pressure.

The pressurization and delivery of fuel is performed by a pressurization mechanism,
The pressurizing mechanism includes a pressurizing device that pressurizes the fuel, and a bypass pipe that bypasses the pressurizing device and connects between pipes through which fuel flows before and after being pressurized by the pressurizing device,
The delivery amount is preferably controlled by controlling the flow rate of the fuel flowing through the bypass pipe using the feedforward control.

The pressurization and delivery of fuel is performed by a pressurization mechanism,
The pressurization mechanism includes a pressurization device that pressurizes the fuel, and a bypass pipe that bypasses the pressurization device and connects between a pipe through which fuel flows before and after the pressurization by the pressurization device. Is a multistage pressurizing mechanism provided in series,
It is preferable that the delivery amount is controlled by controlling the flow rate of the fuel flowing through the bypass pipe in each of the plurality of sets using the feedforward control.

  According to the fuel gas supply system, the fuel gas supply method, and the ship of the above aspect, even if a sudden engine load fluctuation occurs, the fuel gas supply is controlled so as to correspond to the engine load fluctuation, and stable. Fuel gas can be supplied to the engine.

It is a figure which shows an example of a structure of the fuel gas supply system of one Embodiment. It is a figure which shows the example of a structure of the pressurization mechanism of one Embodiment. It is a figure which shows the example of a structure of the pressurization mechanism of other one Embodiment. It is a control block diagram of the example of control which the pressurization control device of one embodiment performs. It is a control block diagram of the example of the control which the pressurization control apparatus of other one embodiment performs. It is a figure which shows the example of the relationship between the correction coefficient used by control of one Embodiment, and setting pressure.

Hereinafter, the fuel gas supply system and the fuel gas supply method of the present invention will be described in detail.
FIG. 1 is a diagram illustrating an example of a configuration of a fuel gas supply system 10 that supplies a boil-off gas of a liquefied gas as a fuel gas to a propulsion engine of a ship according to the present embodiment. Although liquefied natural gas (LNG) is used as the liquefied gas of the fuel gas supply system 10, it is not limited to liquefied natural gas, and liquefied gas such as pure methane gas or ethane gas can be used. The boil-off gas includes, in addition to the gas vaporized by natural heat input in the tank, gas that is forcibly vaporized by intentionally heating LNG (liquefied natural gas). In the present embodiment, description will be made using a gas vaporized by natural heat input in a tank. When using a gas that is forcibly vaporized, a forced vaporizer that forcibly vaporizes the liquefied gas is provided, and the liquefied gas is vaporized before being pressurized.
In this embodiment, the object to be pressurized is boil-off gas, but liquefied gas can also be targeted. In this case, the pressurizing mechanism uses a high-pressure pump that pressurizes the liquefied gas in place of the gas compressor of this embodiment. In this case, after pressurization of the liquefied gas, it is preferable to use a heat exchanger in which the liquefied gas is heated to be in a gas state.

The fuel gas supply system 10 is used to supply boil-off gas vaporized in a tank 20 storing liquefied natural gas as fuel gas to the propulsion engines 40a and 40b in an LNG ship that transports liquefied natural gas. The present embodiment includes a main pipe 31 through which a boil-off gas (hereinafter also referred to as fuel gas) delivered by the pressurizing mechanism 30 flows. In this embodiment, one propulsion engine 40 is provided, but two, three, or four or more propulsion engines may be provided. In this case, the plurality of propulsion engines are connected to branch pipes that are branched from the main pipe 31 and are provided for the respective propulsion engines.
In this specification, the direction in which the boil-off gas is supplied from the tank 20 to the propulsion engine 40 is referred to as the downstream direction, the opposite direction is referred to as the upstream direction, and the downstream side is referred to as the downstream side from a certain reference position. The upstream side from the position is referred to as the upstream side.

The fuel gas supply system 10 of the present embodiment mainly includes a tank 20, a pressurizing mechanism 30, and a liquefaction device 50. A pressurizing mechanism 30 is provided on a main pipe 31 through which boil-off gas extending from the tank 20 to the propulsion engine 40 flows.
The pressurizing mechanism 30 is a device that pressurizes and sends out the boil-off gas vaporized from the liquefied gas in order to supply a part of the boil-off gas to the propulsion engine 40 as a fuel gas.
The liquefying device 50 is a device that liquefies a part of the boil-off gas that has been pressurized and delivered by the pressurizing mechanism 30 and returns it to the tank 20.

(Pressure mechanism)
FIG. 2 is a diagram illustrating an example of the configuration of the pressurizing mechanism 30. The pressurizing mechanism 30 includes gas compressors 32a to 32e, bypass pipes 33a to 33e, adjustment valves 34a to 34e, suction snubbers 35a to 35e, discharge snubbers 36a to 36e, and heat exchangers 37a to 37e. Prepare mainly.
The suction snubbers 35a to 35e are containers provided with spaces configured to temporarily store boil-off gas upstream of the gas compressors 32a to 32e and smoothly suck the boil-off gas into the gas compressors 32a to 32e. The discharge snubbers 36a to 36e are containers provided with spaces configured to temporarily store boil-off gas and smoothly deliver the boil-off gas downstream of the gas compressors 32a to 32e. The heat exchangers 37a to 37e are provided on the downstream side of the discharge snubbers 36a to 36e, and cool the boil-off gas that has become a high temperature by being pressurized.

The gas compressors 32a to 32e are multistage pressurizing devices connected in series for compressing and sending out the boil-off gas. The gas compressors 32a to 32e are portions that suck the boil-off gas in the suction snubbers 35a to 35e and pressurize them to a predetermined pressure. The gas compressors 32a to 32e use, for example, a reciprocating compressor that sucks gas from the suction snubbers 35a to 35e when a movable part (plunger or piston) in the gas compressors 32a to 32e reciprocates linearly, and then pressurizes the gas. be able to. Of the gas compressors 32a to 32e, the oil compressors are used as the gas compressors 32a to 32d, and the oil compressor is used as the gas compressor 32e that pressurizes the boil-off gas at a high pressure. The movable parts of the gas compressors 32a to 32e are driven in conjunction via a rotating shaft that is rotated by the power of a driving source (not shown) whose driving is controlled by the pressurization control device 62. In the gas compressors 32a to 32e, the boil-off gas is compressed stepwise at the same compression rate, so that the boil-off gas is compressed to the fifth power of the compression rate. For example, by compressing the three to four times in each of the gas compressors 32 a to 32 e, BOG is compressed in ³ 5-4 ⁵ times. For example, if the pressure of the boil-off gas on the suction side of the gas compressor 32a is 0.1 MPa, the pressure on the discharge (delivery) side of the gas compressor 32a is about 0.33 MPa, and the pressure on the discharge side of the gas compressor 32b is about 1. The pressure on the discharge side of the gas compressor 32c is about 3.64 MPa, and the pressure on the discharge side of the gas compressor 32d is about 12.06 MPa. Then, the pressure on the discharge side of the gas compressor 32e is increased to a set target pressure, for example, 39.9 Mpa.

The bypass pipe 33a bypasses the gas compressor 32a and connects the suction snubber 35a and the output end of the heat exchanger 37a. That is, the bypass pipe 33a is connected to the pipe portion through which the boil-off gas before being pressurized by the gas compressor 32a flows and the gas compressor 32a. It is a pipe through which boil-off gas flows, connected between pipes through which the boil-off gas after pressurization flows. The bypass pipes 33b to 33d bypass the corresponding gas compressors 32b to 32d and connect the corresponding suction snubbers 35b to 35d and the corresponding output ends of the heat exchangers 37b to 37d, that is, by the gas compressors 32b to 32d. This is a pipe through which boil-off gas flows, connecting a portion of a pipe through which boil-off gas before pressurization flows and a pipe through which boil-off gas after pressurization by the corresponding gas compressors 32b to 32d flows.
The bypass pipe 33e bypasses the gas compressor 32e and connects the suction snubber 35e and the output end of the heat exchanger 37e. That is, the bypass pipe 33e is connected to the pipe portion through which the boil-off gas before being pressurized by the gas compressor 32e flows and the gas compressor 32e. It is a pipe through which boil-off gas flows, connected between pipes through which the boil-off gas after pressurization flows.
The bypass pipes 33a to 33d are provided with adjustment valves 34a to 34e that can adjust the opening degree of the valves. The bypass pipes 33a to 33d are provided with pressure gauges 38a to 38d for measuring the pressure of the boil-off gas pressurized by the gas compressors 32a to 32d. The opening degree of each of the adjusting valves 34a to 34d is adjusted based on the pressure information measured by the pressure gauges 38a to 38d. A pressure gauge 38e that measures the pressure of the boil-off gas after being pressurized by the gas compressor 32e is provided on the downstream side of the bypass pipe 33e in the main pipe 31. The opening degree of the adjustment valve 34e is adjusted based on the pressure information measured by the pressure gauge 38e. Specifically, information on the measured pressure measured by the pressure gauges 38a to 38e is supplied to a pressurization control device 62c (see FIG. 1), which will be described later, and the pressure set as the measured pressure by the pressurization control device 62c. As a control signal for feedback control that controls the amount of boil-off gas that flows through the bypass pipes 33a to 33e based on the difference between the control valves 34a to 34e.

For example, when 1500 kg of boil-off gas is supplied per hour from the upstream side and the gas compressors 32a to 32e pressurize 2000 kg of boil-off gas per hour and send it to the downstream side, 1 to the corresponding bypass pipes 33a to 33e. A boil-off gas of 500 kg per hour is flowed and returned to the upstream side of the gas compressors 32a to 32e. Thus, the opening degree of the adjustment valves 34a to 34e provided in the bypass pipes 33a to 33e is controlled so that 500 kg of boil-off gas flows per hour. Thereby, the pressure on the downstream side of the gas compressors 32a to 32e can be adjusted to a predetermined pressure. By adjusting to the predetermined pressure, the boil-off gas flowing from the pressurizing mechanism 30 toward the propulsion engine 40 can be set to the required pressure and the fuel supply amount required by the propulsion engine 40.
In the present embodiment, bypass pipes 33a to 33e are provided so as to bypass each of the gas compressors 32a to 32e. However, according to one embodiment, at least two of the plurality of adjacent gas compressors 32a to 32e are provided. It is also preferable to adopt a configuration in which a bypass pipe is provided so as to bypass this set of compressors. FIG. 3 is a diagram illustrating an example of a configuration of an embodiment of the pressurizing mechanism 30. In the example shown in FIG. 3, a bypass pipe 33a is provided so as to bypass the gas compressors 32a and 32b at the same time, and a bypass pipe 33c is provided so as to bypass the gas compressors 32c and 32d simultaneously.

2 and 3, a check valve 38 is provided between the fourth stage gas compressor 32d and the fifth stage gas compressor 32e. The gas compressor 32d, which is an oilless compressor, and the gas compressors 32a, 32b, 32c on the upstream side thereof, flow out from the oil compressor, which is included in the boil-off gas sent from the gas compressor 32e, which is an oil compressor. In order to prevent impurities such as oil from flowing in and contaminating the gas compressor 32d and the devices such as the gas compressors 32a, 32b, 32c on the upstream side, a check valve 38 is provided.
According to one embodiment, it is also preferable to provide a check valve between the first-stage gas compressor 32a and the second-stage gas compressor 32b, counting from the upstream side.
Furthermore, according to one embodiment, it is also preferable to provide a check valve on the downstream side of the bypass pipe 33e so that the boil-off gas once supplied to the propulsion engine 40 does not flow backward toward the upstream side.

The extraction pipe branches from between the branch point of the bypass pipe 33b from the main pipe 31 and the junction point of the bypass pipe 33c to the main pipe 31 and is connected to the gas processing device 70 (see FIG. 2 and FIG. 1). The illustration of the gas processing device 70 is omitted). The gas processing device 70 is a device that processes boil-off gas, and examples thereof include a boiler and a generator engine.
The piping extending to the gas processing apparatus 70 is provided with an adjustment valve, and can be configured to adjust the amount of boil-off gas processed by the gas processing apparatus 70.

(Propulsion engine)
The ship used in the present embodiment is provided with a propulsion engine 40. The fuel gas supply system 10 of the present embodiment includes a piping mechanism including a main piping 31 through which the boil-off gas sent from the pressurizing mechanism 30 flows. The propulsion engine 40 may be, for example, a dual fuel engine that can selectively use oil such as heavy oil as fuel while boil-off gas of liquefied gas is used as fuel gas.

  The propulsion engine 40 uses the supplied boil-off gas as fuel gas to burn in the combustion chamber to extract power, and rotates the main shaft 45 and the propeller 46 of the ship. As the propulsion engine 40, for example, a two-stroke cycle low-speed diesel engine can be used.

  The propulsion engine 40 is connected to an engine control unit (hereinafter referred to as ECU) 60, and the drive is controlled by the ECU 60. The ECU 60 is provided on the main pipe 31 that supplies the fuel gas to the propulsion engine 40 so that the main shaft rotation speed measured by the tachometer 42 provided to measure the rotation of the main shaft 45 becomes the target rotation speed. The driving of the propulsion engine 40 is controlled by controlling the opening degree of the pressure control valve 64. That is, the ECU 60 determines the load of the propulsion engine 40 so that the main shaft rotation speed of the main shaft 45 connecting the propulsion engine 40 and the propeller 46 for propulsion becomes the target rotation speed, and controls the pressure of the fuel gas based on this. Device. The ECU 60 determines the load of the propulsion engine 40 so that the main shaft rotational speed that changes due to changes in natural conditions such as weather, sea state winds, and wave heights is maintained at the target rotational speed, as well as operator deceleration, acceleration, turning, etc. The load of the propulsion engine 40 can also be determined according to the operation command value of the propeller rotational speed provided by the instruction. The ECU 60 is configured to set a target pressure on the delivery side of the gas compressor 32e located on the most downstream side based on the determined load, and to send this target pressure to a control integrated device 62c (see FIG. 1) described later. Yes. This target pressure is the required pressure of the fuel gas required by the propulsion engine 40. The control integration device 62c uses this required pressure to control the amount of boil-off gas delivered from the pressurizing device 30. Control of the amount of boil-off gas delivered will be described later.

(Liquefaction device)
The liquefying device 50 is connected to the pressurizing mechanism 30 through an extraction pipe 51 that branches from between a branch point of the bypass pipe 33c from the main pipe 31 and the check valve 38.
The liquefying device 50 is a device that returns boil-off gas that has become unnecessary due to fluctuations in the load of the propulsion engine 40 to the tank 20 as liquefied gas. A part of the boil-off gas is not liquefied and maintains a gas. The boil-off gas is merged with the boil-off gas that is sucked from the tank 20 by the pressurizing device 30 and flows as necessary, and is pressurized by the pressurizing device 30 again. Although not shown, the liquefaction device 50 includes, for example, a heat exchanger that cools the boil-off gas before liquefying the boil-off gas, an expansion valve that expands and liquefies the cooled boil-off gas, and a gas-liquid mixed fluid made by the expansion valve A gas / liquid separator that separates the separated gas, a gas pipe that joins the separated gas to the boil-off gas that is sucked from the tank 20 by the pressurizing device 30, and a liquefied gas pipe that flows the separated liquefied gas to the tank.

(Control of boil-off gas delivery rate by pressurizing mechanism)
For controlling the amount of boil-off gas delivered by the pressurizing mechanism 30 in the present embodiment, the pressurizing mechanism 30, ECU 60, pressure controller 61, pressurization control device 62, pressure control valve 64, and pressure gauge 65 are used. The on-off valve 66 is mainly used. Control of the amount of boil-off gas delivered by the pressurizing mechanism 30 is performed by controlling the amount of boil-off gas flowing through the bypass pipe 33e in the pressurizing mechanism 30. The amount of boil-off gas flowing through the bypass pipe 33e is controlled by controlling the opening degree of the adjustment valve 34e. As will be described later, the opening degree is controlled using control signals FFw, FFv, and FBp generated by the pressurization control device 62.

  The pressure control valve 64 is provided in the main pipe 31 and controls the pressure of the boil-off gas that flows into the downstream portion of the main pipe 31 with respect to the pressurizing mechanism 30 by the opening degree of the pressure control valve 64. The opening degree of the pressure control valve 64 is controlled by a control signal sent from the pressure controller 61. The opening degree of the pressure control valve 64 is controlled so that the pressure measured by the pressure gauge 65 provided in the main pipe 31 becomes the required pressure determined by the ECU 60. In this way, by controlling the pressure of the boil-off gas to be the required pressure, a predetermined amount of boil-off glass is supplied to the propulsion engine 40 as fuel.

  Further, the main pipe 31 is provided with an opening / closing valve 66 for turning on / off the supply of fuel to the propulsion engine 40. On / off of fuel supply by the opening / closing valve 66 is controlled by a control signal from the ECU 60. For example, when starting the propulsion engine 40, the opening / closing valve 66 is opened. When the fuel used by the propulsion engine 40 is changed from boil-off gas to oil such as heavy oil while the drive of the propulsion engine 40 is maintained, the opening / closing valve 66 may be closed while the rotation of the propulsion engine 40 is maintained. Assuming such a case, the opening / closing of the opening / closing valve 66 is controlled by a control signal from the ECU 60. The on-off valve 66 can also be constituted by a gas valve train including a plurality of valves and flow paths.

The ECU 60 sends a control signal to the propulsion engine 40 so that the rotation speed of the propulsion engine 40 becomes a target rotation speed determined according to the set load. Further, the ECU 60 sets the required pressure of the fuel gas required by the propulsion engine 40 according to the load of the propulsion engine 40, and sends information on the required pressure to the pressure controller 61 and the control integrated device 62c (see FIG. 1). send. Further, the ECU 60 sends a gas load signal ACL indicating information on the amount of fuel gas consumed by the propulsion engine 40 by the set load of the propulsion engine 40 to the fuel control device 62 a of the pressurization control device 62. The gas load signal ACL is a signal representing (fuel gas injection rate per revolution of the propulsion engine 40) · (actual speed of the engine 40) / (normal maximum speed of the propulsion engine 40). Here, the fuel gas injection rate is the ratio of the current injection amount when the fuel gas injection amount per rotation when the load of the propulsion engine 40 is 100% is 100%.
The ECU 60 sends the set opening / closing information of the opening / closing valve 66 to the opening / closing valve control device 62 b of the pressurization control device 62.

The control integration device 62c (see FIG. 1) sets the result of adding a constant (constant) pressure to the required pressure of the fuel gas sent to the control integration device 62c as the set pressure Sv. The addition of a constant (constant) pressure (α) to the required pressure (required pressure + α) may cause a drop in pressure in the pressure control valve 64 or the open / close valve 66. If the required pressure is the set pressure Sv, This is because the required pressure of the fuel gas required by the propulsion engine 40 may not be satisfied.
When the amount of pressure decrease in the pressure control valve 64 or the opening / closing valve 66 changes according to the gas load signal ACL of the propulsion engine 40, according to one embodiment, the control integrated device 62c is constant (constant) to the required pressure. It is also preferable to calculate the added pressure in accordance with a predetermined function for the gas load signal ACL, and add this added pressure to the required pressure instead of the constant pressure (α). .
In FIG. 1, the configuration for adding the pressure to the required pressure is not shown.

The pressurization control device 62 includes a fuel control device 62a, an on-off valve control device 62b, and a control integration device 62c.
FIG. 3 is a control block diagram illustrating an example of control performed by the pressurization control device 62.

The fuel control device 62a is a control signal for feedforward control that controls the amount of boil-off gas delivered from the pressurizer 30 based on fluctuations in the gas load signal ACL indicating the amount of fuel gas consumed by the propulsion engine 40. FFw is generated. The generation of the control signal FFw is performed when the fluctuation of the gas load signal ACL is out of a predetermined range. Specifically, the control signal FFw is generated using the FFw function stored and held by the fuel control device 62a with respect to the fluctuation of the gas load signal ACL. The fluctuation of the gas load signal ACL is a time change of the gas load signal ACL sequentially sent from the ECU 60 at a predetermined clock. When the time change deviates from the predetermined range (the change in the gas load signal ACL is large), the pressure measured by the pressure gauge 38e greatly deviates from the set pressure Sv of the fuel gas.
In the example shown in FIG. 3, the set pressure Sv is a pressure obtained by adding a constant (constant) pressure (α) to the required pressure in consideration of the amount of pressure decrease at the pressure control valve 64 or the opening / closing valve 66. Pressure + α). For this reason, when the time change of the gas load signal ACL in the propulsion engine 40 is out of a predetermined range, the pressure of the boil-off gas in the main pipe 31 of the pressurizing mechanism 30 does not change greatly from the set pressure Sv of the fuel gas. The fuel control device 62a controls the amount of boil-off gas delivered from the pressurizing mechanism 30 in accordance with fluctuations in the fuel supply amount.

  For example, the fuel control device 62a calculates using the gas load signal ACL of the propulsion engine 40 and the FFw function, further multiplies a predetermined correction coefficient, and displays the value as an adjustment amount of the opening of the adjustment valve 34e. Generated as the control signal FFw. The generated control signal FFw is sent to the control integration device 62c. The correction coefficient will be described later. The fuel control device 62a of the present embodiment calculates the control signal FFw using the FFw function. However, according to one embodiment, the relationship between the change in the gas load signal ACL and the adjustment amount of the opening of the adjustment valve 34e in advance is obtained. The illustrated reference table may be stored and generated as the control signal FFw by referring to the reference table from the sent gas load signal ACL.

  The on-off valve control device 62b is configured to change the boil-off gas based on a change from on (fully open) to off (fully closed) or off (fully closed) to on (fully open) of the on / off valve 66 provided in the propulsion engine 40. A control signal FFv for feedforward control for controlling the delivery amount is generated. Specifically, when the propulsion engine 40, which is a dual fuel engine, is driven using boil-off gas, and the type of fuel supplied to the propulsion engine 40 is changed from boil-off gas to oil such as heavy oil, The open / close valve 66 is abruptly closed. In this case, since the boil-off gas is prevented from flowing from the opening / closing valve 66 into the piping on the propulsion engine 40 side, the pressure on the main piping 31 on the upstream side of the opening / closing valve 66 and the delivery side portion of the compression mechanism 30 abruptly. It rises and becomes abnormal pressure.

  Further, when the type of fuel supplied to the propulsion engine 40 is changed from oil such as heavy oil to boil-off gas, the opening / closing valve 66a is suddenly opened. In this case, the pressure in the main pipe 31 on the upstream side of the opening / closing valve 66 and the portion on the delivery side of the compression mechanism 30 rapidly decreases. Due to this rapid decrease, the propulsion engine 40 does not exhibit sufficient output sequentially.

For this reason, the on-off valve control device 62b performs feed-forward control for controlling the amount of boil-off gas delivered based on the change information V of the on-off valve 66 provided in the propulsion engine 40 from on to off or off to on. Therefore, the control signal FFv is generated. The generated control signal FFv is sent to the control integration device 62c.
The on-off valve control device 62b calculates, for example, using the change information V of the on-off valve 66 and the FFv function stored and held by the on-off valve control device 62b, and further multiplies a predetermined correction coefficient to obtain the value. The control signal FFv is generated as an adjustment amount of the opening degree of the adjustment valve 34e. Specifically, a control signal FFv that increases or decreases the amount of boil-off gas delivered by a certain amount is generated. The correction coefficient will be described later.
The on-off valve controller 62b of the present embodiment generates the control signal FFv using the FFv function. According to one embodiment, the relationship between the on / off information V and the adjustment amount of the opening of the adjustment valve 34e in advance. It is also preferable to store the reference table indicating the control signal FFv by referring to the reference table from the information V.
When the on-off valve 66 is configured by a gas valve train composed of a plurality of valves and a flow path, according to one embodiment, the valve is turned on and off for each valve and further opened for each valve to be opened. Preferably, the control signal FFv is generated so that the feedforward control is performed.

The control integration device 62c combines the control signals FFw and FFv for the two feedforward controls and a control signal FBp for feeder back control (described later) generated by the control integration device 62c into one control signal FFB. , A device for sending to the adjusting valve 34e of the pressurizing mechanism 30.
The control integrated device 62c controls feedback of the fuel delivery amount of the compression mechanism 30 based on the difference between the set pressure Sv of the propulsion engine 40 and the measured fuel pressure Pv in the main pipe 31 on the delivery side of the compression mechanism 30. A control signal FBp for control is generated. The value of the control signal FBp is expressed as an adjustment amount of the opening degree of the adjustment valve 34e.
The measured pressure Pv is a pressure measured by the pressure gauge 38e, and this pressure is sent to the control integrated device 62c. The set pressure Sv is a pressure (required pressure + α) determined based on the required fuel pressure required for the propulsion engine 40. The required pressure is set to be low at a low load and high at a high load, for example. Such a required pressure is preset according to the propulsion engine 40 and stored in the ECU 60.
The control integration device 62c generates, for example, a control signal FBp for feedback control using PID control with respect to the difference obtained by subtracting the measured pressure Pv and the set pressure Sv.
According to one embodiment, the control integration device 62c stores in advance a reference table showing a relationship between the difference between the set pressure Sv and the measured pressure Pv and the adjustment amount of the opening of the adjustment valve 34e, and the set pressure Sv and It is also preferable to generate the control signal FBp by referring to the reference table from the difference in the measured pressure Pv.

The control integration device 62c adds the control signal FFw sent from the fuel control device 62a, the control signal FFv sent from the opening / closing valve control device 62b, and the control signal FBp generated by the control integration device 62c. One control signal FFB is collected and sent to the adjustment valve 34e of the pressurizing mechanism 30. By controlling the pressure of the boil-off gas in this way, the amount of boil-off gas delivered by the compression mechanism 30 can be controlled. The control integration device 62c controls the opening degree of the adjustment valve 34 by PID control based on the measured pressure Pv sent from the pressure gauge 38e. In this control, a control signal for controlling the opening degree of the adjustment valve 34e is generated and sent to the adjustment valve 34e so that the measured pressure Pv in the pressure gauge 38 falls within a predetermined range.
As described above, the feedforward control and the hoodback control are performed for the opening degree of the adjustment valve 34e provided in the bypass pipe 33e of the gas compressor 32e provided at the most downstream stage of the multistage gas compressor to maximize the pressure of the boil-off gas. To control. As a result, it is possible to most effectively suppress fluctuations in the pressure of the fuel to be supplied in response to a sudden change in the load of the propulsion engine 40 and a sudden change in pressure with respect to on / off of the opening / closing valve 66.

Further, although not shown in FIG. 3, according to one embodiment, the control integration device 62 c includes the control signals FFw and FFv for the two feedforward controls and the measured pressure measured by the pressure gauges 38 a to 38 d. It is also preferable that control signals based on PID control generated based on the difference between the pressure and the preset target pressure are collectively sent to the adjustment valves 34a to 34d of the pressurizing mechanism 30 as one control signal. Moreover, in the multistage pressurization mechanism provided in series with a plurality of sets each including the gas compressors 32a to 32e, the bypass pipes 33a to 33e, and the adjustment valves 34a to 34e, the pressurization control device 62 includes: It is preferable to control the amount of fuel delivered by controlling the opening of each of the plurality of sets of adjusting valves 34a to 34e using a feedforward control signal obtained by adding the control signal FFw and the control signal FFv.
Thereby, the amount of boil-off gas delivered by the pressurizing mechanism 30 can be controlled more efficiently. In particular, it is possible to suppress the pressure in the pressurizing mechanism 30 from becoming an abnormal pressure with respect to a sudden change in the load of the propulsion engine 40 or a sudden change in pressure with respect to the on / off of the opening / closing valve 66, and stable pressurization. Can be maintained.

  As described above, in the control of the fuel delivery amount of the pressurizing mechanism 30 performed by the pressurization control device 62, the on-off valve 66 is turned on (fully opened) from off (fully closed) or off (fully closed) to on (fully opened). ) Includes feed-forward control for controlling the amount of fuel delivered, so that when the fuel type is switched using a dual fuel engine, the opening / closing valve 66 is turned on / off. Even in this case, rapid fluctuations in the pressure of the fuel supplied to the propulsion engine 40 can be suppressed.

In the present embodiment, as shown in FIG. 4, the control signal FFw, the control signal FFv, and the control signal FBp are added to be combined into one control signal FFB, and this control signal FFB is sent to the adjustment valve 34e for adjustment. The opening degree of the valve 34e is controlled. According to one embodiment, as shown in FIG. 5, the control integration device 62c selects one of a control signal obtained by adding the control signal FFw and the control signal FBp, and a control signal having a fixed value (constant value). Further, a switching device 62d for switching may be provided, and a control signal selected by the switching device 62d may be sent to the adjustment valve 34e. FIG. 5 is a control block diagram illustrating an example of control performed by the pressurization control device 62 according to the embodiment.
In this case, the selection of the control signal in the switch 62d is performed based on the change information V of the on-off valve 66 that is a control signal from the ECU 60. Specifically, when the information V is information for closing the opening / closing valve 66, the switching device 62d selects a control signal of a fixed value (constant value), and when the information V is information for opening the opening / closing valve 66, the switching device. 62d selects a control signal obtained by adding the control signal FFw and the control signal FBp. When closing the on-off valve 66, the boil-off gas is not supplied as fuel gas from the pressurizing mechanism 30 to the propulsion engine 40. At this time, since the opening degree of the control valve 34e is constant so that the pressure of the discharge snubber 36e becomes constant, the switch 62d selects a control signal having a fixed value (constant value). The fixed value of the control signal is set so that the pressure of the discharge snubber 36e is constant.

It is preferable that the pressurization control device 62 controls the fuel delivery amount so that the control amount of the fuel delivery amount from the pressurization mechanism 30 is adjusted according to the set pressure Sv. As shown in FIG.
The control signal FFw is corrected by multiplying the control signal FFw of the feedforward control generated by the fuel control device 62a by a correction coefficient determined according to the set pressure Sv sent from the control integration device 62c to the fuel control device 62a. Further, the control signal FFv is corrected by the open / close valve control device 62b multiplying the control signal FFv of the feedforward control by a correction coefficient determined according to the set pressure Sv sent from the control integration device 62c to the open / close valve control device 62b. To do.

FIG. 6 is a diagram illustrating an example of the relationship between the correction coefficient and the set pressure Sv. That is, if the set pressure Sv decreases, the correction coefficient may be decreased.
If the fuel pressure in the main pipe 31 is different, the operation of the pressurizing mechanism 30 may be different even when the fuel delivery amount is changed by the same amount. When the pressurizing mechanism 30 is a multistage gas compressor and the control of the fuel pressure at the time of sending out the boil-off gas of the pressurizing mechanism 30 is performed by the adjustment valve 34e provided in the bypass pipe 33e, the boil-off gas to be pressurized is controlled. When the pressure is different, the opening degree of the adjustment valve 34e for changing the flow rate by the same amount is greatly different. In order to realize more stable control, the amount of boil-off gas (fuel) delivered is changed by changing a correction coefficient that is multiplied by the control signals FFw and FFv in accordance with the set pressure Sv of the propulsion engine 40 in order to correct this difference. Is preferably adjusted.

  The amount of fuel delivered from the pressurizing mechanism 30 may be controlled by controlling the rotational speed of the drive source that drives the gas compressors 32a to 32e. The pressure control device 62 controls the amount of fuel such as boil-off gas delivered from the pressurizing mechanism 30 by controlling all the openings of the adjustment valves 34a to 34e. This is preferable because it can be easily performed.

  By using such a fuel gas supply system 10, a fuel gas supply method as described below can be performed.

That is, when supplying fuel gas to the plurality of propulsion engines 40, the fuel gas supply system 10
(A) In order to supply the boil-off gas vaporized from the tank 20 storing the liquefied gas as the fuel gas to the propulsion engine 40, the boil-off gas vaporized from the liquefied gas or the liquefied gas is pressurized and sent by the pressurizing mechanism 30 as the fuel. Steps,
(B) Based on the difference between the set pressure Sv determined based on the required fuel pressure required by the propulsion engine 40 and the measured pressure Pv of the pressurized fuel, the amount of fuel delivered by the pressurizing mechanism 30 is fed back. Controlling step;
(C) performing a feedforward control on the delivery amount based on fluctuations in the gas load signal ACL indicating the fuel gas consumption of the propulsion engine 40. At this time, the feedforward control is performed when the fluctuation of the gas load signal ACL of the propulsion engine 40 is out of a predetermined range.

Further, the feed forward control for controlling the fuel delivery amount of the pressurizing mechanism 30 based on the change from on to off or off to on of the on-off valve 66 that turns on / off the supply of fuel gas to the propulsion engine 40. Including the steps of:
In the control of the fuel delivery amount by the pressurizing mechanism 30, the control amount of the fuel delivery amount is adjusted according to the set pressure Sv.
Further, the control of the fuel delivery amount by the pressurizing mechanism 30 is performed by controlling the flow rate of the fuel flowing through each of the bypass pipes 33a to 33e.

  The fuel gas supply system, the fuel gas supply method, and the ship according to the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. Of course, you may do it.

DESCRIPTION OF SYMBOLS 10 Fuel gas supply system 20 Tank 30 Pressurization mechanism 31 Main piping 32a-32e Gas compressor 33a-33e Bypass pipe 34a-34e Adjustment valve 35a-35e Suction snubber 36a-36e Discharge snubber 37a-37e Heat exchanger 38 Check valve 38a ~ 38e, 65a, 65b Pressure gauge 40 Propulsion engine 42 Tachometer 45 Main shaft 46 Propeller 50 Liquefaction device 60 Engine control unit 61 Pressure controller 62 Pressurization control device 62a Fuel control device 62b Open / close valve control device 62c Control integration device 64 Pressure control Valve 66 Open / close valve 70 Gas processing device

Claims (11)

A fuel gas supply system for supplying fuel gas to an engine,
A tank for storing liquefied gas;
A pressurizing mechanism that pressurizes and sends out the boil-off gas vaporized from the liquefied gas or the liquefied gas as fuel in order to supply the boil-off gas vaporized from the liquefied gas as a fuel gas to the engine;
A pressurization control device that controls the amount of fuel delivered by the pressurization mechanism;
A main pipe that connects the pressurization mechanism and the engine, and the fuel sent out by the pressurization mechanism flows into the engine,
The control of the delivery amount performed by the pressurization control device is performed by adjusting the delivery amount based on a difference between a set pressure determined based on a required fuel pressure required by the engine and a measured pressure of the fuel in the main pipe. A fuel gas supply system comprising: feedback control for controlling; and feedforward control for controlling the delivery amount based on a change in a gas load signal indicating fuel gas consumption of the engine. The main pipe is provided with an open / close valve for turning on / off the supply of fuel gas to the engine,
The control of the delivery amount performed by the pressurization control device further includes feedforward control for controlling the delivery amount based on information on a change from on to off or from off to on of the opening / closing valve. 2. The fuel gas supply system according to 1.   The fuel gas supply system according to claim 1, wherein the pressurization control device controls the delivery amount so that the control amount of the delivery amount is adjusted according to the set pressure. The pressurizing mechanism includes a pressurizer that pressurizes the fuel, a bypass pipe that bypasses the pressurizer and connects a pipe through which fuel flows before and after pressurization by the pressurizer, and the bypass pipe An adjustment valve that controls the amount of fuel flowing through
The fuel gas supply according to any one of claims 1 to 3, wherein the pressurization control device controls the delivery amount by controlling an opening degree of the adjustment valve using the feedforward control. system. The pressurizing mechanism includes a pressurizer that pressurizes the fuel, a bypass pipe that bypasses the pressurizer and connects a pipe through which fuel flows before and after pressurization by the pressurizer, and the bypass pipe A multistage pressurizing mechanism provided in series with a plurality of sets each including an adjustment valve that controls the amount of fuel flowing through
The said pressurization control apparatus controls the said delivery amount by controlling the opening degree of each adjustment valve of the said multiple sets using the said feedforward control, In any one of Claims 1-3. The fuel gas supply system described. The fuel gas supply system according to any one of claims 1 to 5,
A propulsion engine driven using fuel pressurized by the pressurizing mechanism;
And a control unit for controlling the propulsion engine. A fuel gas supply method for supplying fuel gas to an engine,
In order to supply the boil-off gas vaporized from the tank storing the liquefied gas as a fuel gas to a plurality of engines, pressurizing and sending the boil-off gas vaporized from the liquefied gas or the liquefied gas as fuel; and
Feedback control of the delivery amount based on a difference between a set pressure determined based on a required fuel pressure required by the engine and a measured pressure of the pressurized fuel;
Feedforward control of the delivery amount based on fluctuations in a gas load signal indicating consumption of fuel gas of the engine, and
The feedforward control is performed when the fluctuation of the gas load signal is out of a predetermined range.   The method further includes a step of feedforward control for controlling the delivery amount based on a change from on to off or off to on of an on-off valve that performs on / off of the supply of fuel gas to each engine. 8. The fuel gas supply method according to 7.   The fuel gas supply method according to claim 7 or 8, wherein in the control of the delivery amount, the control amount of the delivery amount is adjusted according to the set pressure. The pressurization and delivery of fuel is performed by a pressurization mechanism,
The pressurizing mechanism includes a pressurizing device that pressurizes the fuel, and a bypass pipe that bypasses the pressurizing device and connects between pipes through which fuel flows before and after being pressurized by the pressurizing device,
The fuel gas supply method according to any one of claims 7 to 9, wherein the control of the delivery amount is performed by controlling a flow rate of fuel flowing through the bypass pipe using the feedforward control. The pressurization and delivery of fuel is performed by a pressurization mechanism,
The pressurization mechanism includes a pressurization device that pressurizes the fuel, and a bypass pipe that bypasses the pressurization device and connects between a pipe through which fuel flows before and after the pressurization by the pressurization device. Is a multistage pressurizing mechanism provided in series,
The fuel according to any one of claims 7 to 9, wherein the control of the delivery amount is performed by controlling the flow rate of the fuel flowing through the bypass pipe in each of the plurality of sets using the feedforward control. Gas supply method.

Images