Gas fuel supply system and vessel

Abstract

To provide a gas fuel supply system which can be miniaturized.SOLUTION: A gas fuel supply system 1 according to an embodiment includes a tank 2 for storing liquid gas, a fuel supply line 3 for leading out the liquid gas from the tank 2, and an evaporator 4 provided in the fuel supply line 3. The gas fuel supply system 1 further includes a tank pressurizing line 6 branched from the fuel supply line 3 in the downstream side of the evaporator 4 or in the evaporator 4 and connected to the tank 2, a first control valve 61 provided in the tank pressurizing line 6, a second control valve 32 provided in the fuel supply line 3 in the downstream side of a branch point of the tank pressurizing line 6, and a processing circuit 8. The processing circuit 8 controls the first control valve 61 on the basis of a pressure detected by a first detector 91 in a state of closing the second control valve 32 when pressurizing the inside of the tank 2, and controls the second control valve 32 on the basis of a pressure or a flow rate detected by a second detector 92 in a state of closing the first control valve 61 when supplying gas fuel to a gas consumption apparatus.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a gas fuel supply system that is installed on a ship and supplies gas fuel derived from liquefied gas to a gas consumer, and to a ship equipped with the gas fuel supply system. [Background technology]

[0002] Some ships are equipped with gas consumers that consume gas fuel to generate power or electricity. For example, gas consumers include reciprocating engines, gas turbine engines, boilers, and fuel cells. A ship may be equipped with one or more gas consumers of the same type, or with multiple gas consumers of different types. Reciprocating engines and gas turbine engines drive propellers or generators, boilers supply steam to steam turbines that drive generators, and fuel cells generate onboard electricity. Such ships are also equipped with gas fuel supply systems that supply gas fuel derived from liquefied gas to the gas consumers.

[0003] For example, Patent Document 1 discloses a gas fuel supply system 100 as shown in Fig. 4. Specifically, the gas fuel supply system 100 includes a tank 110 that stores liquefied gas, a fuel supply line 120 that delivers the liquefied gas from the tank 110, and an evaporator 130 provided in the fuel supply line 120.

[0004] Furthermore, gas fuel supply system 100 includes a pressurizing mechanism 140 that pressurizes the inside of tank 110 so that the liquefied gas can be smoothly discharged from fuel supply line 120. Pressurizing mechanism 140 includes an evaporator 142, an extraction path 141 that guides the liquefied gas from tank 110 to evaporator 142, and a return path 143 that guides the gas evaporated in evaporator 142 to tank 110. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-78448 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the gas fuel supply system 100 of Patent Document 1 has a large overall system size because it includes two evaporators 130 and 142. Since the space inside a ship is limited, it is desirable to make the overall system size as small as possible.

[0007] Therefore, an object of the present disclosure is to provide a gas fuel supply system that can be made compact, and a ship equipped with the gas fuel supply system. [Means for solving the problem]

[0008] From one aspect, the present disclosure provides a gas fuel supply system to be installed on a ship and to supply gas fuel derived from liquefied gas to a gas consumer, the gas fuel supply system comprising: a tank for storing the liquefied gas; a fuel supply line for discharging the liquefied gas from the tank; an evaporator provided in the fuel supply line; a tank pressurization line branching off from the fuel supply line downstream of the evaporator or within the evaporator and leading to the tank; a first control valve provided in the tank pressurization line; a second control valve provided in the fuel supply line downstream of a branch point of the tank pressurization line; a first detector for detecting pressure inside the tank; a second detector for detecting the pressure or flow rate of gas fuel flowing in the fuel supply line downstream of the second control valve; and a processing circuit for controlling the first control valve based on the pressure detected by the first detector when pressurizing the tank, and for controlling the second control valve based on the pressure or flow rate detected by the second detector when supplying gas fuel to the gas consumer.

[0009] From another aspect, the present disclosure provides a ship equipped with the above-described gas fuel supply system. [Effects of the Invention]

[0010] According to the present disclosure, a gas fuel supply system that can be made compact and a ship equipped with the gas fuel supply system are provided. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of a gas fuel supply system according to an embodiment. [Figure 2] FIG. 10 is a schematic configuration diagram of a gas fuel supply system according to a modified example. [Figure 3] FIG. 10 is a schematic configuration diagram of a gas fuel supply system according to another modified example. [Figure 4] FIG. 1 is a schematic diagram of a conventional gas fuel supply system. DETAILED DESCRIPTION OF THE INVENTION

[0012] FIG. 1 shows a gas fuel supply system 1 according to one embodiment. The gas fuel supply system 1 is installed on a ship and supplies gas fuel derived from liquefied gas to gas consumers. The gas consumers consume the gas fuel to generate propulsion power or propulsion or onboard electricity. For example, the gas consumers are reciprocating engines, gas turbine engines, boilers, fuel cells, etc.

[0013] The liquefied gas is not particularly limited, but examples thereof include liquefied hydrogen, LNG (Liquefied Natural Gas), LPG (Liquefied Petroleum Gas), and liquefied ammonia.

[0014] The gas fuel supply system 1 includes a tank 2 that stores liquefied gas, a fuel supply line 3 that connects the tank 2 to the gas consumer, and an evaporator 4 that is provided on the fuel supply line 3. The fuel supply line 3 guides the liquefied gas from the tank 2 to the evaporator 4, and also guides the gas evaporated in the evaporator 4 to the gas consumer as gas fuel. Boil-off gas (BOG) is generated in the tank 2 due to evaporation of the liquefied gas.

[0015] Furthermore, the gas fuel supply system 1 includes a tank pressurization line 6 that branches off from the fuel supply line 3 downstream of the evaporator 4 and connects to the tank 2, a relay line 7 that branches off from the tank pressurization line 6 and connects to the fuel supply line 3, and a processing circuit 8.

[0016] The processing circuit 8 controls the first control valve 61 provided in the tank pressurization line 6, the second control valve 32 and the first switching valve 31 provided in the fuel supply line 3, and the second switching valve 71 provided in the relay line 7. Note that in Fig. 1, some signal lines are not shown to simplify the drawing.

[0017] The tank 2 is a pressure-resistant vessel. In this embodiment, the tank 2 is a double-shelled tank including an inner tank 21 and an outer tank 22. A vacuum layer is formed between the inner tank 21 and the outer tank 22. However, the tank 2 may be a single-shelled tank covered with an insulating material. Alternatively, if the liquefied gas is LPG or liquefied ammonia, the tank 2 may be a single-shelled tank without an insulating material. Also, in this embodiment, the tank 2 is horizontally cylindrical. However, the tank 2 may also be vertically cylindrical. Alternatively, the tank 2 may be spherical or approximately rectangular.

[0018] The fuel supply line 3 extracts liquefied gas from the tank 2. In this embodiment, an upstream portion of the fuel supply line 3 penetrates the tank 2 from the outside to the inside, and the upstream end of the fuel supply line 3 opens near the bottom of the inner tank 21 of the tank 2. The above-mentioned first switching valve 31 is located downstream of the tank 2 and upstream of the evaporator 4, and the above-mentioned second control valve 32 is located downstream of the branch point of the tank pressurization line 6. However, the fuel supply line 3 may also be connected from below the tank 2 to the bottom of the tank 2 so that the liquefied gas is extracted from the bottom of the tank 2.

[0019] The evaporator 4 is a heat exchanger that exchanges heat between the liquefied gas and the heating medium to vaporize the liquefied gas, and is provided across the fuel supply line 3 and the heating line 5 through which the heating medium flows. That is, the evaporator 4 includes an internal flow path 4a for the liquefied gas that constitutes part of the fuel supply line 3, and an internal flow path 4b for the heating medium that constitutes part of the heating line 5. In FIG. 1, the flows in the internal flow paths 4a and 4b are countercurrent, but the flows in the internal flow paths 4a and 4b may also be parallel or cross-current. The heating medium is, for example, antifreeze, hot water, steam, or thermal oil.

[0020] For example, the evaporator 4 may be a microchannel heat exchanger in which multiple metal plates with multiple grooves are stacked and diffusion-bonded together. Alternatively, the evaporator 4 may be a shell-and-tube heat exchanger in which multiple tubes are arranged in a shell, or a plate heat exchanger in which corrugated plates are stacked.

[0021] The downstream portion of the tank pressurization line 6 passes through the tank 2 from the outside to the inside, and the downstream end of the tank pressurization line 6 opens above the liquid level of the liquefied gas inside the tank 2. The relay line 7 branches off from the tank pressurization line 6 downstream of the first control valve 61 and upstream of the tank 2, and is connected to the fuel supply line 3 between the first switching valve 31 and the evaporator 4.

[0022] The processing circuit 8 is electrically connected to a first detector 91 that detects the pressure inside the tank 2, and a second detector 92 that detects the pressure or flow rate of the gas fuel flowing in the fuel supply line 3 downstream of the second control valve 32. In this embodiment, the first detector 91 detects the pressure of the gas layer that is the portion above the liquid level of the liquefied gas inside the tank 2, but the first detector 91 may also detect the pressure of the liquid layer that is the portion below the liquid level.

[0023] With respect to processing circuitry 8, the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0024] When pressurizing the tank 2 without supplying gas fuel to the gas consumer, the processing circuit 8 closes the second switching valve 71 and the second control valve 32 and controls the first control valve 61 based on the pressure detected by the first detector 91 with the first switching valve 31 open. Specifically, the processing circuit 8 controls the aperture of the first control valve 61 so that the pressure detected by the first detector 91 falls within a pressure range in which liquefied gas can be smoothly discharged from the fuel supply line 3. The pressure range is higher than the pressure required by the gas consumer and lower than the design pressure of the tank 2. For example, the pressure range is 0.1 MPaG to 0.5 MPaG if the gas consumer is a boiler or a fuel cell, and 0.5 MPaG to 1.0 MPaG if the gas consumer is a premixed reciprocating engine.

[0025] On the other hand, when gas fuel is supplied to the gas consumer from the tank 2 pressurized to within the pressure range or higher than the pressure range, the processing circuit 8 closes the first control valve 61, and then closes the second selector valve 71 and opens the first selector valve 31, or closes the first selector valve 31 and opens the second selector valve 71. This makes it possible to switch between gas operation, in which a mixture of boil-off gas and vaporized gas in the tank 2 is used as gas fuel, and liquid operation, in which the liquefied gas in the tank 2 is vaporized and used as gas fuel. Note that instead of closing the first control valve 61, a shutoff valve may be provided upstream or downstream of the first control valve 61, and the shutoff valve may be closed.

[0026] For example, the processing circuit 8 performs liquid operation when the pressure inside the tank 2 is within the above-mentioned pressure range, and performs gas operation to actively reduce the pressure inside the tank 2 when the pressure inside the tank 2 is higher than the above-mentioned pressure range and lower than the design pressure of the tank 2. Alternatively, before performing bunkering to fill the tank 2 with liquefied gas, the processing circuit 8 performs gas operation to reduce the pressure inside the tank 2 in preparation for filling. At this time, if there is equipment that can consume gas fuel at relatively low pressure, such as a boiler or fuel cell, it becomes easier to perform gas operation to reduce the pressure inside the tank 2 in preparation for bunkering.

[0027] Whether performing gas operation or liquid operation, the processing circuit 8 controls the second control valve 32 based on the pressure or flow rate detected by the second detector 92. Specifically, the processing circuit 8 controls the opening of the second control valve 32 so that the pressure detected by the second detector 92 becomes the pressure required by the gas consumer, or so that the flow rate detected by the second detector 92 becomes the flow rate required by the gas consumer.

[0028] Furthermore, when pressurizing the tank 2 while supplying gas fuel to the gas consumer, the processing circuit 8 closes the second switching valve 71 and opens the first switching valve 31, controls the first control valve 61 based on the pressure detected by the first detector 91, and controls the second control valve 62 based on the pressure or flow rate detected by the second detector 92.

[0029] As described above, in the gas fuel supply system 1 of this embodiment, the evaporator 4 can be used both for pressurizing the inside of the tank 2 and for generating gas fuel. By using a single evaporator 4 in this manner, the gas fuel supply system 1 can be made compact.

[0030] <Modification> The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0031] For example, as in a modified gas fuel supply system 1A shown in FIG. 2, the tank pressurization line 6 may branch off from the fuel supply line 3 inside the evaporator 4. In this case, it is desirable that the evaporator 4 be provided across the fuel supply line 3 and the two heating lines 51, 52. A heating medium flows through the heating lines 51, 52, similar to the heating line 5 in the above embodiment. The heating media flowing through the heating lines 51, 52 may be the same or different. For example, the heating medium flowing through the heating line 51 may be antifreeze liquid, and the heating medium flowing through the heating line 52 may be hot water.

[0032] More specifically, instead of the internal flow path 4b described in the above embodiment, the evaporator 4 includes an internal flow path 4c corresponding to a portion of the internal flow path 4a upstream of the branch point of the tank pressurization line 6, and an internal flow path 4d corresponding to a portion of the internal flow path 4a downstream of the branch point of the tank pressurization line 6. The internal flow path 4c constitutes a portion of the heating line 51, and the internal flow path 4d constitutes a portion of the heating line 52.

[0033] Internal flow path 4c, which corresponds to the upstream portion of internal flow path 4a, serves to heat and vaporize the liquefied gas, while internal flow path 4d, which corresponds to the downstream portion of internal flow path 4a, serves to heat the vaporized gas to the temperature required by the gas consumer. For example, the temperature of the liquefied gas at the branch point of tank pressurization line 6 is the boiling point of the liquefied gas or slightly higher. By associating internal flow path 4c with the evaporation region (latent heat) of internal flow path 4a and internal flow path 4d with the heating region (sensible heat) of internal flow path 4a, it is possible to achieve an optimized, i.e., compact, flow path design for each.

[0034] As shown in Figure 2, if the tank pressurization line 6 branches off from the fuel supply line 3 inside the evaporator 4, vaporized gas at a temperature close to that of the gas layer inside the tank 2 is returned to the tank 2, resulting in a uniform temperature and density distribution of the gas layer inside the tank 2, and fluctuations in the pressure inside the tank 2 are suppressed and stabilized. This improves the responsiveness of self-pressurization. Furthermore, if the internal flow path 4c is arranged to flow parallel to the internal flow path 4a, it is possible to prevent the heating medium from freezing, and if the internal flow path 4d is arranged to flow counter to the internal flow path 4a, it is possible to achieve compactness and easier temperature adjustment.

[0035] When the tank pressurization line 6 branches off from the fuel supply line 3 inside the evaporator 4, as in a modified gas fuel supply system 1B shown in Fig. 3, a bypass line 63 may be provided that branches off from the tank pressurization line 6 upstream of the first control valve 61 and connects to the fuel supply line 3 between the evaporator 4 and the second control valve 32. Furthermore, a temperature control valve 64 may be provided in the bypass line 63, and a third detector 93 that detects the temperature of the gas fuel may be provided upstream of the second control valve 32. If the temperature control valve 64 is controlled based on the temperature detected by the third detector 93, the temperature of the gas fuel can be controlled more accurately.

[0036] Even when the temperature control valve 64 is controlled based on the temperature detected by the third detector 93 described above, or when the bypass line 63 is not provided, a fourth detector for detecting temperature may be provided in the tank pressurization line 6, and the temperature of the vaporized gas in the tank pressurization line 6 may be controlled by controlling at least one of the flow rate and temperature of the heating medium flowing in the heating line 51 based on the temperature detected by the fourth detector. By providing the tank pressurization line 6 with a temperature control function in this way, it becomes possible to use, for example, high-temperature water, thermal oil, or steam as the heating medium in the heating line 51, whose flow rate and / or temperature are controlled. This widens the temperature difference between the high-temperature side and the low-temperature side, allowing the evaporator 4 to be made more compact. In particular, when the heating medium is steam, the latent heat of condensation can be utilized, allowing the evaporator 4 to be made even more compact.

[0037] Furthermore, when only liquid operation is performed, the first switching valve 31 and the relay line 7 can be omitted.

[0038] <Summary> In a first aspect, the present disclosure provides, from one aspect, a gas fuel supply system to be installed on a ship and to supply gas fuel derived from liquefied gas to a gas consumer, the gas fuel supply system comprising: a tank for storing the liquefied gas; a fuel supply line for discharging the liquefied gas from the tank; an evaporator provided in the fuel supply line; a tank pressurization line branching from the fuel supply line downstream of the evaporator or within the evaporator and leading to the tank; a first control valve provided in the tank pressurization line; a second control valve provided in the fuel supply line downstream of the branch point of the tank pressurization line; a first detector for detecting the pressure inside the tank; a second detector for detecting the pressure or flow rate of gas fuel flowing in the fuel supply line downstream of the second control valve; and a processing circuit for controlling the first control valve based on the pressure detected by the first detector when pressurizing the tank, and for controlling the second control valve based on the pressure or flow rate detected by the second detector when supplying gas fuel to the gas consumer.

[0039] According to the above configuration, the evaporator can be used both for pressurizing the tank and for generating gas fuel. By using a single evaporator in this way, it is possible to make the gas fuel supply system more compact.

[0040] As a second aspect, the gas fuel supply system of the first aspect further includes a first selector valve provided in the gas fuel supply line upstream of the evaporator, a relay line branching from the tank pressurization line downstream of the first control valve and connecting to the gas fuel supply line between the first selector valve and the evaporator, and a second selector valve provided in the relay line, and when supplying gas fuel to the gas consumer, the processing circuit may close the second selector valve and open the first selector valve, or close the first selector valve and the first control valve and open the second selector valve. With this configuration, it is possible to switch between gas operation, in which a mixture of boil-off gas and vaporized gas in a tank is used as gas fuel, and liquid operation, in which liquefied gas in a tank is vaporized and used as gas fuel.

[0041] From another aspect, the present disclosure provides a ship equipped with the above-described gas fuel supply system. [Explanation of symbols]

[0042] 1,1A Gas Fuel Supply System 2 Tanks 3 fuel supply lines 31 First switching valve 32 Second control valve 4. Evaporator 6 Tank pressurization line 61 First control valve 7 Relay Line 71 Second switching valve 8 Processing Circuit 91 Detector 1 92 Second Detector

Claims

1. A gas fuel supply system installed on a ship that supplies gas fuel derived from liquefied gas to a gas consumer, a tank for storing the liquefied gas; a fuel supply line for delivering liquefied gas from the tank; an evaporator provided in the fuel supply line; a tank pressurization line that branches off from the fuel supply line downstream of the evaporator or within the evaporator and leads to the tank; a first control valve provided in the tank pressurization line; a second control valve provided in the fuel supply line downstream of a branch point of the tank pressurization line; a first detector for detecting a pressure in the tank; a second detector that detects the pressure or flow rate of the gas fuel flowing in the fuel supply line downstream of the second control valve; a processing circuit that controls the first control valve based on the pressure detected by the first detector when pressurizing the tank, and controls the second control valve based on the pressure or flow rate detected by the second detector when supplying gas fuel to the gas consumer; A gas fuel supply system comprising:

2. a first switching valve provided in the gas fuel supply line upstream of the evaporator; a relay line branching from the tank pressurization line downstream of the first control valve and connecting to the gas fuel supply line between the first switching valve and the evaporator; A second switching valve provided in the relay line, 2. The gas fuel supply system of claim 1, wherein the processing circuit, when supplying gas fuel to the gas consumer, closes the second switching valve and opens the first switching valve, or closes the first switching valve and the first control valve and opens the second switching valve.

3. A ship equipped with the gas fuel supply system according to claim 1 or 2.

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