JP2018021477A - System and method for supplying fuel gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably supply fuel gas in correspondence with an engine load even when a composition ratio of composition components in the fuel gas varies.SOLUTION: A system for supplying fuel gas includes a plurality of gas compression mechanisms provided in series so as to compress the fuel gas and to make the fuel gas flow from a supply source side of the fuel gas to a propulsion engine side. The gas compression mechanisms respectively include a gas compressor, a suction snapper and a delivery snapper attached to the gas compressor, and a heat exchanger provided in the downstream side of the delivery snapper. A heat exchanger of a first gas compression mechanism of the gas compression mechanisms adjusts a temperature of the fuel gas in a gas output end of the heat exchanger by adjusting cooling performance in accordance with a composition ratio of composition components in the fuel gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel gas supply system and a fuel gas supply method for supplying compressed fuel gas to a propulsion engine of a ship.

  In recent years, various fuel gas supply devices that supply natural gas mainly composed of methane to a propulsion engine of a ship as fuel gas have been proposed. For example, when transporting LNG, boil-off gas that naturally vaporizes from LNG is not only re-liquefied and transported as LNG, but the boil-off gas is effectively used as a fuel gas for a marine propulsion engine. For example, in an LNG carrier that transports LNG, boil-off gas generated during the transportation of LNG is pressurized to a predetermined pressure and supplied to the propulsion engine as fuel gas.

In order to convert a low-pressure gas such as boil-off gas into a high-pressure gas, the gas is compressed using a multistage compressor. A multistage compressor consists of several compressors connected in series, for example (patent document 1).
Furthermore, it is also known that fuel gas is pressurized to about 30 MPa using a multistage compressor and supplied to a gas injection valve of an engine (MC-GI engine) (Non-patent Document 1).

Japanese Patent Laid-Open No. 8-219088

"Achievements of Large Gas Injection Diesel Engine (MC-GI Engine)", Tetsugo Fukuda et al., Journal of the JIME Vol.36, No.9, pp.64-70

The engine (MC-GI engine) that pressurizes the fuel gas to about 30 MPa using the multistage compressor and supplies it to the gas injection valve (MC-GI engine) is an onshore power generation engine, and is basically premised on operation at a substantially constant load. A low-speed diesel engine, and a multistage gas compressor may supply fuel gas at a substantially constant pressure.
On the other hand, when such a multistage compressor (gas compressor) is applied to a low-speed diesel engine for marine propulsion, the engine load changes with time, so the operation of the multistage compressor (gas compressor) is also changed. There is a need. For example, the load torque of a ship's propeller fluctuates due to deceleration, acceleration, turning by a ship maneuver, or changes in natural conditions such as weather, sea-like winds, wave heights, etc. The operating load varies. In order to cope with this change in engine load, it is required to supply a stable fuel gas according to the gas supply amount required by the engine.
In recent years, shale gas-derived commercial ethane has attracted attention as a fuel for marine propulsion engines, in addition to natural gas mainly composed of methane. However, commercial ethane (liquid fuel) different from methane contains methane and the like in addition to ethane, and the composition ratio differs between the boil-off gas and the liquid state. Specifically, in the boil-off gas, the composition ratio of methane is higher than that in the liquid case. In addition, among the boil-off gas, the composition ratio of the composition component differs between the naturally vaporized gas (NBOG: Natural Boil Off Gas) and the forced vaporized gas (FBOG: Forced Boil Off Gas), and the composition ratio of NBOG methane and ethane. Also changes with storage days. For this reason, since the density and calorific value of the fuel gas also change, in a fuel supply system having a multistage compressor (gas compressor), the fuel gas is supplied to the multistage compressor (gas compressor) under certain conditions (temperature, pressure). ) May be excessive or deficient in the amount of compressed fuel gas with respect to the engine load, that is, the fuel gas supply may become unstable.

  Therefore, the present invention provides a fuel gas supply system and a fuel gas supply method capable of stably supplying a fuel gas according to the engine load even when the composition ratio of the composition component in the fuel gas changes. For the purpose.

One embodiment of the present invention is a fuel gas supply system. The fuel gas supply system compresses the fuel gas and supplies the propulsion engine from the fuel gas supply source side in order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship. A plurality of gas compression mechanisms provided in series.
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A heat exchanger provided on the downstream side of the discharge snapper in the flow direction of the fuel gas toward the propulsion engine, which adjusts the temperature of the fuel gas compressed by the gas compressor.
The heat exchanger of the first gas compression mechanism among the plurality of gas compression mechanisms adjusts the cooling capacity in accordance with the composition ratio of the composition component in the fuel gas, whereby the gas output end of the heat exchanger The temperature of the fuel gas at is adjusted.

  It is preferable that a refrigerant temperature adjustment unit that adjusts the temperature of the refrigerant flowing through the heat exchanger of the first gas compression mechanism according to the composition ratio is provided.

  In that case, it is preferable that the said refrigerant | coolant temperature adjustment part raises the temperature of the said refrigerant | coolant, so that the density of the said fuel gas becomes high with the said composition ratio.

  At this time, the temperature of the fuel gas compressed by the gas compressor of the gas compression mechanism adjacent to the downstream side in the flow direction with respect to the gas compressor of the first gas compression mechanism is equal to or lower than the heat resistant temperature of the gas compressor. The refrigerant temperature adjusting unit preferably adjusts the temperature of the refrigerant.

  It is preferable that a branch path connected to a recovery device for recovering the fuel gas from a flow path of the fuel gas between the discharge snapper of the first gas compression mechanism and the heat exchanger is provided.

  A discharge snapper of the first gas compression mechanism or a gas output end of the discharge snapper, and a heat exchanger of another gas compression mechanism provided upstream of the gas compressor of the first gas compression mechanism in the flow direction. It is preferable to provide a bypass pipe that connects the gas input end without passing through the gas compressor of the first gas compression mechanism.

The bypass pipe is provided with a valve for adjusting the flow rate of the fuel gas flowing through the bypass pipe toward the gas input end of the heat exchanger of the another gas compression mechanism,
Furthermore, it is preferable that a control unit that adjusts the opening degree of the valve according to the pressure of the fuel gas in the discharge snapper of the first gas compression mechanism is provided.

Furthermore, another aspect is a fuel gas supply system. The fuel gas supply system is
In order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship, the fuel gas is compressed and sent from the fuel gas supply side to the propulsion engine side in series. A plurality of gas compression mechanisms are provided.
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A heat exchanger provided on the downstream side of the discharge snapper in the flow direction of the fuel gas toward the propulsion engine, which adjusts the temperature of the fuel gas compressed by the gas compressor.
A second gas compression mechanism of the plurality of gas compression mechanisms includes a plurality of series of gas compression mechanism lines including the gas compressor, the suction snapper and the discharge snapper in parallel.
The second gas compression mechanism includes a drive adjustment unit that stops driving of at least one of the plurality of series of gas compression mechanism lines in accordance with a composition ratio of composition components in the fuel gas.

At that time, the second gas compression mechanism is a most downstream gas compression mechanism located on the most downstream side in the flow direction,
A discharge snapper of the most downstream gas compression mechanism, or a gas output end of the discharge snapper, and a heat exchanger of another gas compression mechanism provided upstream of the gas compressor of the most downstream gas compression mechanism in the flow direction. It is preferable to provide a bypass pipe that connects the gas input end without going through the gas compressor of the most downstream gas compression mechanism.

Further, at that time, the bypass pipe is provided with a valve for adjusting the flow rate of the fuel gas flowing through the bypass pipe toward the gas input end of the heat exchanger of the another gas compression mechanism,
Furthermore, it is preferable that a control unit that adjusts the opening degree of the valve according to the discharge snapper of the most downstream gas compression mechanism or the pressure of the fuel gas at the gas output end of the discharge snapper is provided.

Further, the second gas compression mechanism is a most downstream gas compression mechanism located on the most downstream side in the flow direction,
Of the plurality of gas compression mechanisms, when a gas compression mechanism adjacent to the upstream side in the flow direction with respect to the most downstream gas compression mechanism is referred to as a first gas compression mechanism, a heat exchanger of the first gas compression mechanism is It is preferable that the temperature of the fuel gas at the gas output end of the heat exchanger is adjusted by adjusting the cooling capacity of the heat exchanger according to the composition ratio.

  In that case, it is preferable to provide a refrigerant temperature adjusting unit that adjusts the temperature of the refrigerant flowing through the heat exchanger of the first gas compression mechanism according to the composition ratio of the composition components in the fuel gas.

  Furthermore, at that time, it is preferable that the refrigerant temperature adjusting unit increases the temperature of the refrigerant as the density of the fuel gas increases.

  Further, the refrigerant temperature adjusting unit adjusts the temperature of the refrigerant so that the temperature of the fuel gas compressed by the gas compressor of the most downstream gas compression mechanism is equal to or lower than the heat resistant temperature of the gas compressor. preferable.

  In addition, it is preferable that a branch path connected to a recovery device for recovering the fuel gas from the fuel gas supply line between the discharge snapper of the first gas compression mechanism and the heat exchanger is provided.

  At that time, the fuel gas flows from the downstream side in the flow direction to the upstream side between the connection position of the branch path on the fuel gas supply line and the heat exchanger of the first gas compression mechanism. It is preferable that a check valve for preventing this is provided.

  A first gas supply source configured to supply, as the fuel gas, a naturally vaporized boil-off gas naturally vaporized from the liquid fuel to the most upstream gas compression mechanism located at the most upstream in the flow direction among the plurality of gas compression mechanisms; The forced vaporization boil-off gas having a composition ratio different from that of the natural vaporization boil-off gas, which is forcibly vaporized from the liquid fuel according to the fuel gas requirement of the propulsion engine that exceeds the supply amount of the natural vaporization boil-off gas, And a second gas supply source for supplying to the most upstream gas compression mechanism.

Yet another embodiment of the present invention is a fuel gas supply method. The fuel gas supply method is performed in a fuel gas supply system. The fuel gas supply system includes:
In order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship, the fuel gas is compressed and sent from the fuel gas supply side to the propulsion engine side in series. A plurality of gas compression mechanisms provided,
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A heat exchanger that adjusts the temperature of the fuel gas compressed by the gas compressor and is provided closer to the propulsion engine than the discharge snapper. The fuel gas supply method is
Supplying fuel gas to the propulsion engine after being compressed in stages by each gas compression mechanism;
The heat exchanger of the first gas compression mechanism among the plurality of gas compression mechanisms adjusts the cooling capacity in accordance with the composition ratio of the composition component in the fuel gas, whereby the gas output end of the heat exchanger Adjusting the temperature of the fuel gas.

Still another embodiment of the present invention is a fuel gas supply method. The fuel gas supply method is performed in a fuel gas supply system. The fuel gas supply system includes:
In order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship, the fuel gas is compressed and sent from the fuel gas supply side to the propulsion engine side in series. A plurality of gas compression mechanisms provided,
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A plurality of gas compression mechanisms, comprising: a heat exchanger provided on a side of the propulsion engine with respect to the discharge snapper for adjusting a temperature of the fuel gas compressed by the gas compressor. The second gas compression mechanism includes a plurality of series of gas compression mechanism lines including the gas compressor, the suction snapper, the discharge snapper, and the heat exchanger in parallel. The fuel gas supply method includes:
Supplying fuel gas to the propulsion engine after being compressed in stages by each gas compression mechanism;
The second gas compression mechanism includes a step of stopping driving of at least one of the plurality of series of gas compression mechanism lines in accordance with a composition ratio of composition components in the fuel gas.

  According to the fuel gas supply system and the fuel gas supply method of the above aspect, even when the composition ratio of the component components of the fuel gas changes, the fuel gas can be stably supplied according to the engine load.

It is a figure which shows an example of a structure of the fuel gas supply system which supplies a high pressure fuel gas to the propulsion engine of the ship of this embodiment. It is a figure which shows an example of a structure of the principal part of the fuel gas supply system shown in FIG. It is a figure explaining the flow volume of the fuel gas which the gas compressor of this embodiment discharges in a downstream direction, and the flow volume of the fuel gas which flows backward through a bypass pipe toward an upstream direction. It is a ph diagram of an example when the fuel gas which has ethane as a main component is used for the fuel gas supply system of this embodiment. It is a ph diagram of an example when another fuel gas which has ethane as a main component is used for the fuel gas supply system of this embodiment. It is a ph diagram of an example when another fuel gas which has ethane as a main component is used for the fuel gas supply system of this embodiment. It is a ph diagram of an example when methane is used as fuel gas for the fuel gas supply system of this embodiment.

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 high-pressure fuel gas to a marine vessel propulsion engine according to the present embodiment. FIG. 2 is a diagram showing an example of a peripheral configuration including a main part of the fuel gas supply system shown in FIG. 1, specifically, a fifth stage gas compression mechanism. The fuel gas supply system 10 uses liquid fuel, for example, commercial ethane gas, as the fuel gas, but is not limited thereto. Methane gas or natural gas can be used. The fuel gas includes a gas (FBOG) obtained by intentionally heating the liquid fuel and forcibly vaporizing the liquid fuel, in addition to the gas (NBOG) in which the liquid fuel is naturally vaporized.

  The fuel gas supply system 10 is used in a ship to pressurize and supply fuel gas to the propulsion engine 14. In the present embodiment, the direction in which the fuel gas is supplied from the fuel gas supply source 12 to the propulsion engine 14 is referred to as the downstream direction, the opposite direction is referred to as the upstream direction, and the downstream side from the reference position is referred to as the downstream side. An upstream side from a reference position is called an upstream side.

The fuel gas supply system 10 of the present embodiment pressurizes the fuel gas and propels it from the fuel gas supply source 12 side in order to supply the fuel gas to the propulsion engine 14 that receives the supply of the fuel gas and propels the ship. First to fifth stage gas compression mechanisms 13a to 13e that flow to the engine 14 side are provided. The first to fifth stage gas compression mechanisms 13a to 13e are provided in series.
The first to fifth stage gas compression mechanisms 13a to 13e include gas compressors 16a to 16e, suction snappers 18a to 18e, discharge snappers 20a to 20e, heat exchangers 22a to 22e, bypass pipes 24a to 24e, The control valve 26a-26e, the valve control parts 28a-28e, the refrigerant | coolant temperature adjustment part 30, and the temperature control apparatus 32 are mainly provided.

The fuel gas supply source 12 includes a first gas supply source 12a and a second gas supply source 12b. The first gas supply source 12a supplies NBOG, which is naturally vaporized from the liquid fuel stored in the storage tank, as fuel gas to the first stage gas compression mechanism 13a that is the most upstream gas compression mechanism. The second gas supply source 12b supplies FBOG that is forcibly vaporized from the liquid fuel to the first stage gas compression mechanism 13a as a fuel gas. At this time, when the first gas supply source 12a has a supply amount of NBOG that satisfies the fuel gas requirement amount of the propulsion engine 14, the gas source adjustment unit 12c gives priority to only the NBOG to the first stage gas compression mechanism 13a. Adjust to supply. On the other hand, when the fuel gas requirement amount of the propulsion engine 14 exceeds the NBOG supply amount of the first gas supply source 12a, the gas source adjustment unit 12c responds to the fuel gas requirement amount of the propulsion engine 14 exceeding the NBOG supply amount. In addition to NBOG, adjustment is made so that FBOG is supplied as fuel gas to the first stage gas compression mechanism 13a. Therefore, the second gas supply source 12b supplies FBOG as the fuel gas to the first stage gas compression mechanism 13a according to the fuel gas requirement amount of the propulsion engine 14 exceeding the NBOG supply amount. Note that the gas composition of FBOG is different from the gas composition of NBOG. For example, in the case of commercial ethane, which is a liquid fuel, NBOG has a higher composition ratio of methane, which is more easily vaporized than ethane, compared to FBOG. Therefore, the gas composition of the fuel gas changes depending on the engine load. Further, since the composition of the liquid fuel changes according to the storage days of the liquid fuel due to natural vaporization of methane, the composition of the NBOG also changes according to the storage days of the liquid fuel. In the case of commercial ethane, the composition ratio of methane varies between 0 mol% and 30 mol%. In some cases, liquefied natural gas containing methane as a main component (for example, methane composition 100 mol%) is used as a fuel instead of commercial ethane. For this reason, the composition ratios of the composition components in the fuel gas supplied to the first to fifth stage gas compression mechanisms 13a to 13e change. Therefore, in the present embodiment, as described later, the drive of the fourth stage gas compression mechanism 13d or the fifth stage gas compression mechanism 13e can be adjusted according to the composition ratio of the composition components in the fuel gas. It is configured.
The ship to which this embodiment is applied may be a transport ship that transports liquid fuel as a load, or can be applied to ships other than the transport ship.

The propulsion engine 14 burns the supplied fuel gas in the combustion chamber to extract power, and rotates the main shaft 15a and the propeller 15b. As the propulsion engine 14, for example, a two-stroke cycle low-speed diesel engine can be used.
The propulsion engine 14 is connected to the governor 15c, and the drive of the propulsion engine 14 is controlled by the governor 15c. The governor 15c is provided in a supply line that supplies fuel gas to the propulsion engine 14 so that the main shaft rotation speed measured by the tachometer 15d provided to measure the rotation of the main shaft 15a becomes the target rotation speed. The drive of the propulsion engine 14 is controlled by controlling the opening of a flow control valve (not shown). That is, the governor 15c determines the load of the propulsion engine 14 so that the main shaft rotation speed of the main shaft 15a connecting the propulsion engine 14 and the propeller 15b for propulsion becomes the target rotation speed, and based on this, determines the fuel gas requirement amount. This is a device that controls the fuel supply amount based on the required fuel gas amount. The governor 15c determines the load of the propulsion engine 14 so that the main shaft rotational speed, which changes due to changes in natural conditions such as weather, sea state wind, and wave height, is maintained at the target rotational speed, as well as operator deceleration, acceleration, and turning. The load of the propulsion engine 14 can also be determined according to the operation command value of the propeller rotation speed provided by such an instruction. The governor 15c is configured to set a target pressure on the discharge side of the gas compressor 16e located on the most downstream side based on the determined load and to send the target pressure to the valve control unit 28e. This target pressure is the fuel supply pressure required by the propulsion engine 14. The valve control unit 28e sets a target value of the pressure of the fuel gas in the discharge snapper 20e based on the sent target pressure.

The gas compressors 16a to 16e are multi-stage compressors connected in series to compress the fuel gas and flow it from the fuel gas source 12 side to the propulsion engine 14 side in order to supply the fuel gas to the propulsion engine 14. . The gas compressors 16a to 16e are portions that suck and pressurize the fuel gas in the suction snappers 18a to 18e to a predetermined pressure. As the gas compressors 16a to 16e, for example, a reciprocating compressor in which gas is sucked into a cylinder by a reciprocating motion of a movable part (plunger or piston) in the gas compressors 16a to 16e and then compressed can be used. . Of the gas compressors 16a to 16e, the gas compressors 16a to 16d are oilless compressors, and the oil compressor is used as the gas compressor 16e that pressurizes the fuel gas to a high pressure of 30 MPa or more. The movable parts of the gas compressors 16a to 16e are driven in conjunction via a crankshaft that is rotated by the power of the drive source (not shown) (for example, an electric motor). In the gas compressors 16a to 16e, the fuel gas is compressed stepwise at the same compression rate, so that the fuel 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 16a to 16e, the fuel gas is compressed to ³ 5-4 ⁵ times. For example, if the pressure of the fuel gas on the suction side of the gas compressor 16a is 0.1 MPa, the pressure on the discharge side of the gas compressor 16a is about 0.4 MPa, the pressure on the discharge side of the gas compressor 16b is about 1.2 MPa, gas The pressure on the discharge side of the compressor 16c is about 3.9 MPa, and the pressure on the discharge side of the gas compressor 16d is about 12 to 13 MPa. Then, the pressure on the discharge side of the gas compressor 16e is increased to the set target pressure.

  The suction snappers 18a to 18e are provided to prevent pulsation of the fuel gas associated with the gas compressors 16a to 16e, respectively, and temporarily store the fuel gas before compression provided on the upstream side of the gas compressors 16a to 16e. It is a container. Accordingly, the pressure in the suction snappers 18a to 18e corresponds to the pressure of the fuel gas immediately before being pressurized by the gas compressors 16a to 16e.

  The discharge snappers 20a to 20e are provided to prevent pulsation of the fuel gas in association with the gas compressors 16a to 16e, respectively, and temporarily store the compressed fuel gas provided on the downstream side of the gas compressors 16a to 16e. It is a container. Pressure gauges 19a to 19e for measuring the pressure of the fuel gas stored therein or the pressure of the fuel gas at the gas output end are provided at or near the discharge snappers 20a to 20e. The measurement results of the pressure gauges 19a to 19e are sent to valve controllers 28a to 28e described later. The discharge snappers 20a to 20e are provided with a safety valve (not shown) that opens the valve at a predetermined pressure.

  As the heat exchangers 22a to 22e are attached to the gas compressors 16a to 16e, the temperature of the fuel gas, which is increased by the compression of the fuel gas in each of the gas compressors 16a to 16e, is changed between the fuel gas and the refrigerant. Is a device for adjusting the temperature by heat exchange. The heat exchangers 22a to 22e are provided downstream of the discharge snappers 20a to 20e in the flow direction of the fuel gas toward the propulsion engine 14. The refrigerant in the heat exchangers 22a to 22e is not particularly limited, but water can be used. The heat exchangers 22a to 22d are connected to suction snappers 18b to 18e located on the downstream sides of the heat exchangers 22a to 22d via supply lines.

The bypass pipes 24a and 24b are provided between the gas output ends of the fuel gas of the heat exchangers 22a and 22b associated with the gas compressors 16a and 16b and the suction snappers 18a and 18b associated with the gas compressors 16a and 16b, respectively. The gas compressors 16a and 16b are connected without going through.
The bypass pipes 24c, 24d, and 24e are connected to the gas compressors 16c, 16d, and 16e, respectively, or the gas output ends of the fuel gas of the discharge snappers 20c, 20d, and 20e, and the gas compressors 16c and 16d. , 16e between the gas input terminals of the heat exchangers 22b, 22c, 22d associated with the gas compressors 16b, 16c, 16d provided upstream of the fuel gas flow direction. It is connected without going through 16e.

The bypass pipes 24a to 24e are provided with control valves 26a to 26e for controlling the amount of fuel gas flowing.
The opening degree of each of the control valves 26a to 26e depends on the pressure of the fuel gas in the discharge snapper 20a to 20e associated with the corresponding gas compressor 16a to 16e, or the gas output of the fuel gas in the discharge snapper 20a to 20e or the discharge snapper 20a to 20e. Control is performed so that the pressure of the fuel gas at the end becomes a preset target value of the pressure. That is, the flow rate of the fuel gas flowing through the bypass pipes 24a to 24e is equal to the pressure of the fuel gas in the corresponding discharge snapper 20a to 20e or the pressure of the fuel gas at the gas output end of the discharge snapper 20a to 20e or the discharge snapper 20a to 20e. Controlled based on. The bypass pipes 24a and 24b connect the gas output ends of the heat exchangers 22a and 22b and the suction snappers 18a and 18b. The pressure of the fuel gas at the gas output ends of the heat exchangers 22a and 22b is as follows. This is the same as the pressure of the fuel gas at the gas output ends of the discharge snappers 20a, 20b.

  FIG. 3 is a diagram for explaining the flow rate of the fuel gas discharged from the gas compressor 16b in the downstream direction and the flow rate of the fuel gas flowing backward through the second bypass pipe 24b in the upstream direction. FIG. 3 illustrates the flow of the second-stage gas compressor 16b and the second bypass pipe 24b, but the same behavior is also obtained in the other gas compressors 16a, 16c to 16e and bypass pipes 24a and 24c to 24e. Therefore, the gas compressor 16b and the bypass pipe 24b will be described as a representative. As shown in FIG. 3, for example, when 1500 kg of fuel gas per hour is supplied from the upstream side and the gas compressor 16b compresses 2000 kg of fuel gas per hour and discharges it downstream, the bypass pipe 24b is Then, 500 kg of fuel gas per hour is made to flow backward and returned to the suction snapper 18b. Thus, the opening degree of the control valve 26b is controlled so that 500 kg of fuel gas per hour flows backward from the discharge snapper 20b. Thereby, 1500 kg of fuel gas can flow constantly from the gas output end of the heat exchanger 22b to the downstream side per hour. Therefore, the pressure of the fuel gas in the discharge snapper 20b can be kept constant.

In the present embodiment, a branch path 35 is provided that branches from a gas supply line between the second-stage gas compression mechanism 13b and the third-stage gas compression mechanism 13c toward the boiler 34 that uses part of the fuel gas. ing. The flow rate of the fuel gas branched to the boiler 34 is adjusted by a valve 36 provided in the branch path 35.
Further, in the present embodiment, a branch path 39 is provided from the fuel gas supply line between the discharge snapper 20d of the fourth stage gas compression mechanism 13d and the heat exchanger 22d toward the recovery device 38. The recovery device 38 is a device that recovers the fuel gas. The recovered fuel gas may be returned to the first gas supply source 12a or the like, or the recovered fuel gas may be reliquefied. The branch path 39 is provided with a heat exchanger 40 and a valve 42, the temperature of the fuel gas is adjusted by the heat exchanger 40, and the flow rate of the fuel gas recovered by the valve 42 is adjusted.

In the present embodiment, a check valve 44 is provided between the branch position of the bypass pipe 24a on the fuel gas supply line and the suction snapper 18b, and the branch position of the branch path 39 on the fuel gas supply line. And a connection position of the bypass pipe 24e on the fuel gas supply line, a check valve 46 is provided, and the branch position of the bypass pipe 24e on the fuel gas supply line and the gas input end of the heat exchanger 22e Between the two, a check valve 48 is provided.
The check valve 44 is provided between the first stage gas compression mechanism 13a and the second stage gas compression mechanism 13b, and is provided to prevent the fuel gas from flowing back to the fuel gas supply source 12 side. It is done. If the check valve 44 is provided on the fuel gas supply source 12 side with respect to the suction snapper 18a, the check valve 44 is difficult to open because the pressure difference for reopening after the check valve 44 is closed is small. For this reason, the check valve 44 cannot be provided on the fuel gas supply source 12 side with respect to the suction snapper 18a.
The check valve 46 is a first to fourth stage gas compression mechanism in which the oil component contained in the fuel gas due to the gas compressor 16e of the oil supply compressor uses the gas compressors 16a to 16d of the oilless compressor. By flowing back to 13a to 13d, the first to fourth stage gas compression mechanisms 13a to 13d are prevented from being contaminated with oil.
The check valve 48 prevents the fuel gas on the supply line between the heat exchanger 22e and the propulsion engine 14 from flowing back to the discharge snapper 20e side.

  In the present embodiment, the temperature of the refrigerant used in the heat exchanger 22d of the fourth stage gas compression mechanism 13d is adjusted by the refrigerant temperature adjustment unit 30. The refrigerant temperature adjusting unit 30 adjusts the temperature of the refrigerant in accordance with a control instruction from the temperature control device 32. The refrigerant temperature adjustment unit 30 includes a heater that heats the refrigerant, a heat exchanger that cools the refrigerant, and the like. The temperature control device 32 sets the temperature of the refrigerant according to the composition ratio of the composition components in the fuel gas. For example, the temperature of the refrigerant is set according to the type of liquefied natural gas or liquefied commercial ethane. Furthermore, in the case of liquefied commercial ethane, the composition ratio of methane and ethane in the fuel gas varies depending on the number of storage days, so the temperature of the refrigerant is determined based on the actual analysis of the composition ratio of the composition components in the current fuel gas. The composition ratio of the composition component in the current fuel gas may be estimated based on the fuel storage days, and the refrigerant temperature may be set according to the estimation result. Further, as described above, since the composition ratios of the NBOG and FBOG composition components are also different, the composition ratio of the composition components is estimated according to the supply amount of NBOG and FNOG, and the refrigerant temperature is set according to the estimation result. May be. Further, since the composition ratio of the NBOG and FBOG composition components changes according to the storage days, the composition ratio of the composition components is estimated according to the storage days and the supply amount of NBOG and FNOG, and the refrigerant is determined according to the estimation result. The temperature may be set.

  Thus, in the heat exchanger 22d, the temperature of the refrigerant is adjusted in accordance with the composition ratio of the composition components of the fuel gas (for example, the composition ratio of methane and ethane) because the density of the fuel gas depends on the composition of the fuel gas. This is because it varies greatly depending on the situation. As described above, the first to fifth stage gas compression mechanisms 13a to 13e pressurize the fuel gas to a predetermined pressure, and the flow rate of the fuel gas flowing through the bypass pipes 24a to 24e is the discharge snapper 20a to 20e or the discharge. Since control is performed based on the pressure of the fuel gas at the gas output ends of the snappers 20a to 20e, the amount of fuel gas pressurized by each gas compression mechanism and flowing to the downstream gas compression mechanism or the propulsion engine 14 is the amount of fuel gas It is adjusted by pressure. For this reason, when the density of the fuel gas changes, the amount (mass) of the fuel gas changes even if the pressure of the fuel gas is the same. On the other hand, regardless of the composition ratio of the composition components in the fuel gas, the change in the lower heating value (LCV) per unit mass is small. For example, the LCV of methane is 50000 kcal / kg, and the LCV of ethane is 47500 kcal / kg). Although the amount (mass) of the fuel gas supplied to the propulsion engine 14 that outputs the same load must be constant even if the composition ratio of the composition components in the fuel gas changes, the fuel gas is at the pressure of the fuel gas. In the first to fifth stage gas compression mechanisms 13a to 13e for adjusting the amount of the fuel gas, the amount (mass) of the fuel gas supplied to the propulsion engine 14 changes when the density of the fuel gas changes. In the present embodiment, instead of directly controlling the amount (mass) of the fuel gas, even if the composition ratio of the composition component of the fuel gas is changed, the change in the density of the fuel gas is suppressed. The temperature is adjusted by the heat exchanger 22d.

The density of the fuel gas at the gas output end of the heat exchanger 22d of the fourth-stage gas compression mechanism 13d of the present embodiment is, for example, about 80 kg in the case of fuel gas containing methane as a main component (composition ratio exceeds 50%). / ^m is ^3, is a case of a fuel gas 180～300Kg / ^{m 3} for ethane as a main component (composition ratio is more than 50%) of. At the gas output end of the heat exchanger 22d, the temperature of the fuel gas is controlled by the heat exchanger 22d so as to be a predetermined temperature. For this reason, when the fuel gas containing ethane as the main component is used, the first to fifth stage gas compression mechanisms 13a to 13e are driven under the same conditions as when the fuel gas containing methane as the main component is used. If the fuel gas is supplied to the propulsion engine 14, the fuel gas becomes excessive, which is not preferable from the viewpoint of energy saving. Further, when the fuel gas mainly containing methane is used, the first to fifth stage gas compression mechanisms 13a to 13e are driven under the same conditions as the case where the fuel gas mainly containing ethane is used and the same load state is obtained. When fuel gas is supplied to the propulsion engine 14, the fuel gas becomes deficient.
This problem also occurs in a fuel gas mainly composed of ethane originating from commercial ethane in which the composition ratio of the composition components changes.

For this reason, in the present embodiment, the temperature of the refrigerant used in the heat exchanger 22d is adjusted so that the change in the density of the fuel gas caused by the composition ratio of the composition components in the fuel gas becomes small. That is, in the present embodiment, the temperature of the fuel gas at the gas output end of the heat exchanger 22d is adjusted by adjusting the cooling capacity in the heat exchanger 22d according to the composition ratio of the composition components in the fuel gas. Yes. For this reason, even if the composition ratio of the composition components in the fuel gas changes, the fuel gas can be stably supplied according to the load of the propulsion engine 14. For example, in the case of fuel gas mainly composed of methane, the temperature of the refrigerant is, for example, 38 ° C., and the temperature of the fuel gas at the gas output end of the heat exchanger 22d is 45 ° C. In the case of fuel gas mainly composed of ethane, the temperature of the refrigerant is, for example, 62 ° C., and the temperature of the fuel gas at the gas output end of the heat exchanger 22d is 70 ° C. As a result, the density of the fuel gas containing ethane as a main component is reduced as compared with the case where the temperature of the refrigerant is not adjusted (for example, maintained at 38 ° C.). For example, the density 230 kg / ^{m 3} drops to a density 180 kg / ^{m 3.} In the above description, the fuel gas mainly composed of ethane and the fuel gas mainly composed of methane gas have been described as an example. However, even in the fuel gas originating from the same commercial ethane, the composition ratio of the composition components is as described above. Since it changes, the above-mentioned problem can be solved by adjusting the cooling capacity in the heat exchanger 22d according to the composition ratio of the composition component in the fuel gas.

  In the present embodiment, as shown in FIG. 2, the fifth-stage gas compression mechanism 13e (second gas compression mechanism) includes a gas compressor 16e, a suction snapper 18e, and a discharge snapper 20e. A mechanism line is provided in parallel. That is, the fifth stage gas compression mechanism 13e includes another gas compression mechanism including a gas compression mechanism line including a gas compressor 16e1, a suction snapper 18e1, and a discharge snapper 20e1, and a gas compressor 16e2, a suction snapper 18e2, and a discharge snapper 20e2. A mechanism line is provided in parallel. In the present embodiment, the fifth-stage gas compression mechanism 13e includes two series of gas compression mechanism lines, but may include three, four, or more gas compression supply lines.

  The fifth stage gas compression mechanism 13e includes a drive adjustment unit 50 mechanically connected to the gas compressors 16e1 and 16e2, and a drive control device 52. The drive adjusting unit 50 stops driving at least one of the gas compression mechanism lines in accordance with the control instruction of the drive control device 52. The drive control device 52 sets the number of gas compression mechanism lines to be driven according to the composition ratio of the composition components in the fuel gas, and sets the gas compression mechanism lines that are not driven. Therefore, the drive adjustment unit 50 stops driving one of the two series of gas compression mechanism lines in accordance with the composition ratio of the composition component in the fuel gas. The drive control device 52 stops one drive of one gas compression mechanism line depending on, for example, whether the fuel gas is mainly composed of methane or the fuel gas mainly composed of ethane. As described above, when the fuel gas mainly composed of ethane is used, the fuel gas mainly composed of methane having a lower density than ethane is used to stop one driving of the gas compression mechanism line. If the first to fifth stage gas compression mechanisms 13a to 13e are driven under the same conditions as in the case of using the fuel gas to supply fuel gas to the propulsion engine 14 in the same load state, the first to fifth stage gas compression mechanisms 13a are used. This is because the amount (mass) of the fuel gas becomes excessive because the amount of fuel gas to the propulsion engine 14 is controlled by pressure. That is, when the fuel gas mainly composed of methane is used, the drive adjusting unit 60 drives two series of gas compression mechanism lines. When the fuel gas mainly composed of ethane is used, the drive adjustment unit 60 is one series of gas compression mechanism lines. Drive only. As described above, even if the temperature of the fuel gas at the gas output end of the heat exchanger 22d is adjusted according to the composition ratio of the composition component of the fuel gas, it is difficult to make the change in the density of the fuel gas constant, When the fuel gas becomes excessive, only one series of gas compression mechanism lines can be driven and the remaining one series of gas compression mechanism lines can be stopped. In this case, it is preferable that the recovery device 38 recovers excess fuel gas. As described above, the density of the fuel gas mainly composed of ethane is 2 to 4 times larger than the density of the fuel gas mainly composed of methane. In the present embodiment, since only one gas compression mechanism line is driven out of the two gas compression mechanism lines according to the composition ratio, it is necessary to compress excess fuel gas by the fifth stage gas compression mechanism. Disappear. For this reason, even if the composition ratio of the composition components in the fuel gas changes, the fuel gas can be stably supplied.

  As described above, in the fuel gas supply system 10 of this embodiment, the temperature of the refrigerant is adjusted in order to adjust the cooling capacity of the heat exchanger 22d of the fourth stage gas compression mechanism 13d. The amount may be adjusted. However, the refrigerant temperature adjusting unit 30 adjusts the temperature of the refrigerant flowing through the heat exchanger 22d of the fourth stage gas compression mechanism 13d (first gas compression mechanism) according to the composition ratio of the composition components in the fuel gas. However, it is preferable from the viewpoint that the change in the density of the fuel gas due to the change in the composition ratio can be reliably reduced and the fuel gas can be stably supplied. More specifically, the refrigerant temperature adjustment unit 30 preferably increases the temperature of the refrigerant as the density of the fuel gas increases depending on the composition ratio of the composition components in the fuel gas.

  Fuel compressed by the gas compressor 16e of the fifth stage gas compression mechanism 13e adjacent to the downstream side in the fuel gas flow direction with respect to the gas compressor 16d of the fourth stage gas compression mechanism 13d (first gas compression mechanism). It is preferable that the refrigerant temperature adjusting unit 30 adjust the temperature of the refrigerant so that the gas temperature is equal to or lower than the heat resistant temperature of the gas compressor 16e, for example, the cylinder seal heat resistant temperature (for example, 140 ° C.). For example, when using a fuel gas mainly composed of ethane, the refrigerant temperature adjusting unit 30 preferably increases the temperature in order to reduce the density of the fuel gas compressed by the gas compressor 16e. The seal heat resistance temperature may be exceeded and the durability of the gas compressor 16e may not be maintained. For this reason, as for the refrigerant temperature adjustment part 30, the range of the temperature of a refrigerant | coolant is restrict | limited.

  As described in the present embodiment, the recovery apparatus recovers the fuel gas from the fuel gas supply line between the discharge snapper 20d of the fourth stage gas compression mechanism 13d (first gas compression mechanism) and the heat exchanger 22d. It is preferable to provide a branch path 39 connected to 38. Thus, the amount of fuel gas pressurized by the fifth-stage gas compression mechanism 13e can be adjusted along with the adjustment of the flow rate of the fuel gas flowing through the bypass pipe 24d, so that excess fuel gas can be compressed by the fifth-stage gas compression. It is possible to suppress pressurization by the mechanism 13e and contribute to effective use of energy.

  In the present embodiment, since the bypass pipe 24d is provided in the fourth gas compression mechanism 13d, unnecessary fuel gas that is not supplied to the fifth-stage gas compression mechanism 13e of the fuel gas is cooled by the heat exchanger 22d. Without returning to the gas input end of the heat exchanger 22c of the upstream third stage gas compression mechanism 13c. The fuel gas passes through the heat exchanger 22c, is cooled, and is brought to a predetermined temperature set initially at the gas output end of the heat exchanger 22c. For this reason, even if it is pressurized by the gas compressor 16d, the fuel gas controlled to a constant temperature can flow to the heat exchanger 22d, and the temperature of the fuel gas at the gas output end of the heat exchanger 22d is accurately controlled. can do.

  In the present embodiment, the bypass pipe 24d is provided with a valve 26d for adjusting the flow rate of the fuel gas, and the opening degree of the valve 26d is adjusted according to the pressure of the fuel gas in the discharge snapper 20d. Even if the load changes, the fuel gas supply can be stably controlled.

  The fifth-stage gas compression mechanism 13e, which is the most downstream gas compression mechanism, has a bypass pipe that connects the gas output end of the discharge snapper 20e and the gas input end of the heat exchanger 22d without going through the gas compressor 16e. The fuel gas unnecessary for supplying the propulsion engine 14 can be returned to the gas input end of the heat exchanger 22d, and the temperature of the fuel gas is maintained at a predetermined temperature before and after pressurization by the gas compressor 16e. can do. The bypass pipe 24e is provided with a valve 26e for adjusting the flow rate of the fuel gas, and the opening of the valve 26e is adjusted according to the pressure of the fuel gas at the gas output end of the discharge snapper 20e. Even if changes, the fuel gas supply can be stably controlled.

  Further, a fifth-stage gas compression mechanism 13e, which includes a plurality of gas compression mechanism lines and can stop driving at least one gas compression mechanism line in accordance with the composition ratio of the fuel gas composition components, In the fourth stage gas compression mechanism 13d, even if the composition ratio of the fuel gas composition component is changed by combining with the heat exchanger 22d that adjusts the temperature of the refrigerant according to the composition ratio of the fuel gas composition component. The effect of supplying a stable fuel gas according to the engine load is increased.

  As shown in FIG. 1, the fuel gas flows from the downstream side in the fuel gas flow direction to the upstream side between the connection position of the branch path 39 on the fuel gas supply line and the heat exchanger 22d. Since the check valve 46 is provided to prevent the oil component contained in the fuel gas from flowing into the recovery device 38 due to the gas compressor 16e of the oil compressor, the recovery device 38 causes oil contamination. Prevent receiving.

  In the present embodiment, the bypass pipe 24c of the third stage gas compression mechanism 13c connects the discharge snapper 20c and the gas input end of the heat exchanger 22b, but the bypass pipe 24c is the fuel gas of the heat exchanger 22c. It is also preferable to connect the gas output end and the gas input end of the heat exchanger 22b. Thereby, the rise in pressure at the gas output end of the fuel gas of the discharge snubber 20b of the second stage gas compression mechanism 13b can be suppressed. In particular, when the supply of the fuel gas to the propulsion engine 14 is stopped, the fuel gas in the third and fourth stage gas compression mechanisms 13c and 13d passes through the bypass pipe 24c and the discharge snubber 20b of the second stage gas compression mechanism 13b. Therefore, the pressure at the gas output end of the fuel gas of the discharge snubber 20b is likely to rise. However, by connecting the gas output end of the fuel gas of the heat exchanger 22c and the gas input end of the heat exchanger 22b through the bypass pipe 24c, the fuel gas whose temperature has dropped through the heat exchanger 22c is discharged from the discharge snubber 20b. Since it returns to the gas output end, the temperature of the fuel gas at the gas output end of the fuel gas of the discharge snubber 20b decreases and the density of the fuel gas increases. As a result, the amount of fuel gas that can be accumulated in the space of the discharge snapper 20b connected to the gas output end of the discharge snubber 20b increases, the pressure increase rate is reduced, and the pressure increase can be suppressed.

  In the present embodiment, the heat exchanger for adjusting the temperature of the refrigerant is the heat exchanger 22d of the fourth stage gas compression mechanism 13d, but depending on the type of fuel gas, the heat exchanger is limited to the fourth stage gas compression mechanism 13d. Not. This is a heat exchanger of the part of the gas compression mechanism in which the density of the fuel gas rapidly changes to a predetermined value or more due to the compression of the fuel gas when the gas compression mechanism of each stage is viewed in order from the first stage gas compression mechanism 13a. Good. Further, the place where a plurality of gas compression mechanism lines are provided and at least one of the gas compression supply lines can be stopped is not limited to the fifth stage gas compression mechanism 13e.

In such a fuel gas supply system 10, the following fuel gas supply method is performed.
(1) a step of compressing fuel gas in stages in each of the first to fifth stage gas compression mechanisms 13a to 13e and supplying the fuel gas to the propulsion engine;
(2) The heat exchanger 22d of the fourth stage gas compression mechanism 13d among the first to fifth stage gas compression mechanisms 13a to 13e adjusts the cooling capacity in accordance with the composition ratio of the composition components in the fuel gas. Thus, the step of adjusting the temperature of the fuel gas at the gas output end of the heat exchanger 22d is performed.

In the fuel gas supply system 10, the following fuel gas supply method is performed.
(3) The step of compressing the fuel gas in stages by each gas compression mechanism and supplying it to the propulsion engine;
(4) The fifth stage gas compression mechanism 13e performs a step of stopping driving of at least one of the plurality of series of gas compression mechanism lines in accordance with the composition ratio of the composition component in the fuel gas.

  4 to 7 are ph diagrams of an example when methane gas is used as the fuel gas or fuel gas mainly containing ethane gas is used in the fuel gas supply system 10 of the present embodiment. 4 shows an example in which the composition of the fuel gas is 100 mol% ethane, FIG. 5 shows an example in which the composition of the fuel gas is 85 mol% ethane and 15 mol% methane, and FIG. An example in which the composition is ethane 70 mol% and methane 30 mol% is shown, and FIG. 7 shows an example in which the composition of the fuel gas is methane 100 mol%. The fuel gas starts from the state 1s (see FIG. 1) of the fuel gas immediately before being supplied to the suction snapper 18a. The fuel gas states 1s to 5s, 1d to 5d, and X shown in FIGS. 4 to 7 are the fuel gas states at the positions shown in FIGS. Table 1 below shows examples of the pressures and temperatures of the fuel gas states 1 s to 5 s, 1 d to 5 d, and X when the fuel gas supply method of the present embodiment is performed. The change in the fuel gas when the pressure is reduced by passing through the bypass pipes 24a to 24e is an isenthalpy change, and corresponds to a portion moving downward in the figure in FIGS.

As shown in FIG. 1, the bypass pipe 24b of the second stage gas compression mechanism 13b connects the suction snapper 18b of the gas compressor 16b pressurized to a predetermined pressure and the gas output end of the heat exchanger 22b. When the flow returns to the suction snapper 18b, the temperature of the fuel gas decreases due to an isenthalpy change (change along the arrow going downward in FIGS. 4 to 7 from the state 2s). However, since this temperature decrease is 5 ° C. or less as shown in FIGS. 4 to 7, the density of the fuel gas is substantially constant, and the amount (mass) of the pressurized and discharged fuel gas is kept constant. Is done.
On the other hand, the bypass pipes 24c and 24d of the third and fourth stage gas compression mechanisms 13c and 13d are piped so that the fuel gas returns to the gas input ends of the heat exchangers 22b and 22c. Even if the temperature of the fuel gas that has returned to the gas input end of 22c is lowered due to a change in isoenthalpy, the temperature is adjusted by the heat exchangers 22b and 22c to 45 ° C. as shown in states 3s and 4s in Table 1. Therefore, the density of the fuel gas sucked by the gas compressors 16c and 16d of the third and fourth stage gas compression mechanisms 13c and 13d is constant, and the amount (mass) of the pressurized fuel gas is maintained constant.

As can be seen from Table 1, the state 5s is the state of the fuel gas after passing through the heat exchanger 22d, and is a fuel gas containing ethane as a main component (ethane 100 mol%; ethane 85 mol%; methane 15 mol%; In the case of ethane 70 mol% and methane 30 mol%, the temperature of the fuel gas is set higher than that of the fuel gas of 100% methane. Thereby, the raise of the density of fuel gas can be suppressed. Further, unnecessary fuel gas that is not supplied to the propulsion engine 14 is returned to the gas input end of the heat exchanger 22d by the bypass pipe 24e.
On the other hand, if the temperature of the state 5s is increased without limitation, the temperature of the state 5d exceeds 140 ° C. and exceeds the cylinder seal heat resistance temperature of the gas compressor 16e. For this reason, in order to reduce the density of the fuel gas, the temperature in the state 5 s cannot be increased without limitation. For example, with a fuel gas of 70 mol% ethane and 30 mol% methane, if the temperature in state 5s is 70 ° C., the temperature in state 5d exceeds 140 ° C. or 140 ° C., which is problematic in terms of heat resistance of the gas compressor 16e. . For this reason, in this embodiment, it is preferable to set the temperature range (upper limit temperature) of the refrigerant of the heat exchanger 22d.

  The fuel gas supply system and the fuel gas supply method of 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 it is also good.

DESCRIPTION OF SYMBOLS 10 Fuel gas supply system 12 Fuel gas supply source 12a 1st gas supply source 12b 2nd gas supply source 12c Gas source adjustment part 13a-13e 1st-5th stage | paragraph gas compression mechanism 14 Propulsion engine 15a Main shaft 15b Propeller 15c Governor 15d Rotation Total 16a-16e, 16e1, 16e2 Gas compressor 18a-18e, 18e1, 18e2 Suction snapper 19a-19e Pressure gauge 20a-20e, 20e1, 20e2 Discharge snapper 22a-22e, 40 Heat exchanger 24a-24e Bypass pipe 26a-26e Control Valves 28a to 28e Valve control unit 30 Refrigerant temperature adjustment unit 32 Temperature control device 34 Boiler 35, 39 Branch path 36, 42 Valve 38 Recovery device 44, 46, 48 Check valve 50 Drive adjustment unit 52 Drive control device

Claims (19)

In order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship, the fuel gas is compressed and sent from the fuel gas supply side to the propulsion engine side in series. Provided with a plurality of gas compression mechanisms provided,
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A heat exchanger provided on the downstream side of the discharge snapper in the flow direction of the fuel gas toward the propulsion engine to adjust the temperature of the fuel gas compressed by the gas compressor,
The heat exchanger of the first gas compression mechanism among the plurality of gas compression mechanisms adjusts the cooling capacity in accordance with the composition ratio of the composition component in the fuel gas, whereby the gas output end of the heat exchanger The fuel gas supply system characterized by adjusting the temperature of the said fuel gas in.   2. The fuel gas supply system according to claim 1, further comprising a refrigerant temperature adjustment unit that adjusts a temperature of a refrigerant flowing through a heat exchanger of the first gas compression mechanism in accordance with the composition ratio.   The fuel gas supply system according to claim 2, wherein the refrigerant temperature adjustment unit increases the temperature of the refrigerant as the density of the fuel gas increases according to the composition ratio.   The refrigerant so that the temperature of the fuel gas compressed by the gas compressor of the gas compression mechanism adjacent to the downstream side in the flow direction with respect to the gas compressor of the first gas compression mechanism is equal to or lower than the heat resistant temperature of the gas compressor. The fuel gas supply system according to claim 3, wherein the temperature adjustment unit adjusts the temperature of the refrigerant.   5. The apparatus according to claim 1, further comprising a branch path connected to a recovery device that recovers the fuel gas from a flow path of the fuel gas between a discharge snapper of the first gas compression mechanism and a heat exchanger. The fuel gas supply system described in 1.   A discharge snapper of the first gas compression mechanism or a gas output end of the discharge snapper, and a heat exchanger of another gas compression mechanism provided upstream of the gas compressor of the first gas compression mechanism in the flow direction. The fuel gas supply system according to any one of claims 1 to 5, further comprising a bypass pipe that connects a gas input end without passing through a gas compressor of the first gas compression mechanism. The bypass pipe is provided with a valve for adjusting the flow rate of the fuel gas flowing through the bypass pipe toward the gas input end of the heat exchanger of the another gas compression mechanism,
Furthermore, the fuel gas supply system of Claim 6 provided with the control part which adjusts the opening degree of the said valve according to the pressure of the said fuel gas in the discharge snapper of the said 1st gas compression mechanism. In order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship, the fuel gas is compressed and sent from the fuel gas supply side to the propulsion engine side in series. Provided with a plurality of gas compression mechanisms provided,
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A heat exchanger provided on the downstream side of the discharge snapper in the flow direction of the fuel gas toward the propulsion engine to adjust the temperature of the fuel gas compressed by the gas compressor,
A second gas compression mechanism of the plurality of gas compression mechanisms includes a plurality of series of gas compression mechanism lines including the gas compressor, the suction snapper and the discharge snapper in parallel.
The second gas compression mechanism includes a drive adjustment unit that stops driving of at least one of the plurality of series of gas compression mechanism lines in accordance with a composition ratio of composition components in the fuel gas. Gas supply system. The second gas compression mechanism is a most downstream gas compression mechanism located on the most downstream side in the flow direction,
A discharge snapper of the most downstream gas compression mechanism, or a gas output end of the discharge snapper, and a heat exchanger of another gas compression mechanism provided upstream of the gas compressor of the most downstream gas compression mechanism in the flow direction. The fuel gas supply system according to claim 8, further comprising a bypass pipe that connects a gas input end without passing through a gas compressor of the most downstream gas compression mechanism. The bypass pipe is provided with a valve for adjusting the flow rate of the fuel gas flowing through the bypass pipe toward the gas input end of the heat exchanger of the another gas compression mechanism,
10. The fuel gas according to claim 9, further comprising a control unit that adjusts an opening degree of the valve in accordance with a discharge snapper of the most downstream gas compression mechanism or a pressure of the fuel gas at a gas output end of the discharge snapper. Supply system. The second gas compression mechanism is a most downstream gas compression mechanism located on the most downstream side in the flow direction,
Of the plurality of gas compression mechanisms, when a gas compression mechanism adjacent to the upstream side in the flow direction with respect to the most downstream gas compression mechanism is referred to as a first gas compression mechanism, a heat exchanger of the first gas compression mechanism is The temperature of the fuel gas at the gas output end of the heat exchanger is adjusted by adjusting the cooling capacity of the heat exchanger according to the composition ratio, according to any one of claims 8 to 10. The fuel gas supply system described.   The fuel gas supply system according to claim 11, further comprising a refrigerant temperature adjusting unit that adjusts a temperature of the refrigerant flowing through the heat exchanger of the first gas compression mechanism in accordance with a composition ratio of composition components in the fuel gas.   The fuel gas supply system according to claim 12, wherein the refrigerant temperature adjustment unit increases the temperature of the refrigerant as the density of the fuel gas increases.   The refrigerant temperature adjusting unit adjusts the temperature of the refrigerant so that the temperature of the fuel gas compressed by the gas compressor of the most downstream gas compression mechanism is equal to or lower than the heat resistant temperature of the gas compressor. The fuel gas supply system described.   The branch path connected to the collection | recovery apparatus which collect | recovers fuel gas from the supply line of the said fuel gas between the discharge snapper and heat exchanger of a said 1st gas compression mechanism is provided. The fuel gas supply system described in 1.   The fuel gas is prevented from flowing from the downstream side to the upstream side in the flow direction between the connecting position of the branch path on the fuel gas supply line and the heat exchanger of the first gas compression mechanism. The fuel gas supply system according to claim 15, wherein a check valve is provided.   A first gas supply source configured to supply, as the fuel gas, a naturally vaporized boil-off gas naturally vaporized from the liquid fuel to the most upstream gas compression mechanism located at the most upstream in the flow direction among the plurality of gas compression mechanisms; The forced vaporization boil-off gas having a composition ratio different from that of the natural vaporization boil-off gas, which is forcibly vaporized from the liquid fuel according to the fuel gas requirement of the propulsion engine that exceeds the supply amount of the natural vaporization boil-off gas, The fuel gas supply system of any one of Claims 1-16 provided with the 2nd gas supply source supplied to the said most upstream gas compression mechanism as. In order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship, the fuel gas is compressed and sent from the fuel gas supply side to the propulsion engine side in series. A plurality of gas compression mechanisms provided,
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A fuel gas supply system comprising: a heat exchanger provided on a side of the propulsion engine with respect to the discharge snapper for adjusting a temperature of the fuel gas compressed by the gas compressor;
Supplying fuel gas to the propulsion engine after being compressed in stages by each gas compression mechanism;
The heat exchanger of the first gas compression mechanism among the plurality of gas compression mechanisms adjusts the cooling capacity in accordance with the composition ratio of the composition component in the fuel gas, whereby the gas output end of the heat exchanger Adjusting the temperature of the fuel gas in the method. In order to supply the fuel gas to the propulsion engine that receives the supply of the fuel gas and propels the ship, the fuel gas is compressed and sent from the fuel gas supply side to the propulsion engine side in series. A plurality of gas compression mechanisms provided,
Each of the gas compression mechanisms is
A gas compressor for compressing the fuel gas and supplying the fuel gas at a predetermined pressure from the fuel gas supply source side to the propulsion engine side in order to supply the fuel gas to the propulsion engine;
A suction snapper and a discharge snapper provided on the suction side and the discharge side of the gas compressor, so as to accompany the gas compressor;
A plurality of gas compression mechanisms, comprising: a heat exchanger provided on a side of the propulsion engine with respect to the discharge snapper for adjusting a temperature of the fuel gas compressed by the gas compressor. The second gas compression mechanism is provided with a plurality of series of gas compression mechanism lines including the gas compressor, the suction snapper and the discharge snapper, and a heat exchanger in parallel,
Supplying fuel gas to the propulsion engine after being compressed in stages by each gas compression mechanism;
The second gas compression mechanism includes a step of stopping driving of at least one of the plurality of series of gas compression mechanism lines in accordance with a composition ratio of composition components in the fuel gas. Supply method.

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