JP2005038832A - Boil-off gas treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve an effective utilization of boil-off gas generated from a liquid fuel and miniaturization and weight-saving of the boil-off gas treatment device for a vehicle mounting a fuel cell. <P>SOLUTION: This device has a liquid fuel tank 14 to store the liquid fuel to be mounted on the vehicle and a fuel gas supply passage 13 to supply the gasified fuel from the liquid fuel tank 14 to the fuel cell 12 or a hydrogen engine 60, and a boil-off gas supply passage 19 to supply the boil-off gas generated from the liquid fuel into the fuel gas supply passage 13 is connected to the fuel gas supply passage 13, and a mixed gas in which the boil-off gas and the fuel are mixed is supplied to the fuel cell 12 or the hydrogen engine 60. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a boil-off gas processing system, and more particularly, to recover boil-off gas generated from liquid fuel mounted on an automobile by converting it into electric energy.

In recent years, electric vehicles and hybrid vehicles use liquid fuel to generate electric power in a fuel cell or the like, and serve as an electric power source for driving an automobile motor.
As this type of liquid fuel, liquid hydrogen, liquefied methane, or the like is usually used. In a fuel cell vehicle, the liquid fuel is stored in a tank and mounted on the vehicle.
When liquid fuel is stored in a fuel tank, external heat is transferred into the tank during storage, and gas generated by vaporization of the internal liquid fuel, that is, boil-off gas, may fill the tank. If this boil-off gas is left as it is, it is dangerous because the pressure inside the tank rises, so it is necessary to remove the boil-off gas.

Regarding a boil-off gas processing apparatus in such a fuel cell vehicle, for example, in Japanese Patent Application Laid-Open No. 2003-56799 (Patent Document 1), a hydrogen storage alloy tank containing a hydrogen storage alloy is provided in the vehicle, After the generated boil-off gas is stored in the hydrogen storage alloy, the hydrogen storage alloy is heated to separate the hydrogen, store it under high pressure, and supply it to the fuel cell as necessary. Techniques for treating boil-off gas are disclosed.
JP 2003-56799 A

  However, in the boil-off gas processing apparatus as described above, the hydrogen storage alloy tank that adsorbs the boil-off gas, the means for heating the hydrogen storage alloy, and the hydrogen separated from the hydrogen storage gold are temporarily stored under high pressure. A pressurizing means is required. When heating means and pressurizing means are provided in a vehicle having a limited space, there is a problem that it is difficult to reduce the size and weight of the vehicle.

  The present invention has been made in view of the above problems, and it is an object of the present invention to reduce the size and weight of a boil-off gas processing apparatus that processes boil-off gas generated from liquid fuel in a vehicle equipped with liquid fuel.

In order to solve the above problems, as a first invention, there is provided a processing system for boil-off gas generated from liquid fuel for a fuel cell mounted on a vehicle,
A boil-off gas generated in a path for circulating the liquid fuel from the liquid fuel tank as a refrigerant to the inside of the liquid fuel tank mounted on the vehicle and / or equipment other than the fuel cell is supplied to the fuel cell and allowed to react with the fuel cell. The present invention provides a boil-off gas processing system characterized by generating electricity.

  According to the above configuration, the boil-off gas generated in the liquid fuel tank or / and the boil-off gas generated in the path for supplying the refrigerant to other equipment as a refrigerant are supplied to the fuel cell and reacted to convert the boil-off gas into electric energy. Can be recovered as energy. By using this boil-off gas, the electric power generated by the fuel cell can be used for driving an automobile.

A second invention is a processing system for boil-off gas generated from liquid fuel made of liquid hydrogen mounted on a vehicle,
A boil-off gas made of gaseous hydrogen generated in a refrigerant path for circulating liquid hydrogen from the liquid hydrogen tank is supplied to the hydrogen engine inside the liquid hydrogen tank mounted on the vehicle and / or for the refrigerant of the equipment, and the hydrogen engine generates electric power. The boil-off gas processing system is characterized by operating the machine.

  That is, the second invention is not a fuel cell as a power generator, but a hydrogen engine and a generator operated by the hydrogen engine. Therefore, liquid hydrogen is used as a fuel cell, and the liquid hydrogen is used as a refrigerant. When it is used and circulated, the boil-off gas vaporized in the circulation path and in the hydrogen fuel tank is recovered and supplied to the hydrogen engine of the power generation device in the same manner as in the first aspect of the invention for effective use. .

The surplus power generated by the generator operated by the fuel cell or the hydrogen engine is used for charging the secondary battery.
In this way, when excessive power is generated, the secondary battery connected to the fuel cell is supplied and stored for charging, so that the energy of the boil-off gas can be used effectively.
Therefore, it is not necessary to store the boil-off gas in the form of a gas, and a conventional pressurizing unit and a heating unit for taking out the stored gas become unnecessary.
As the type of the secondary battery, a known secondary battery such as a lead battery, a nickel metal hydride battery, or a lithium ion battery can be appropriately selected and used.

  A superconducting motor using a superconducting coil is used as a motor for driving the vehicle, and the superconducting motor is driven by electric power supplied from a generator operated by the fuel cell or the hydrogen engine. The motor is accommodated in a refrigerant circulation jacket, and a refrigerant path for circulating a part of the liquid fuel in the liquid fuel tank as a refrigerant is provided in the refrigerant circulation jacket and a boil-off gas supply path is branched and connected to the refrigerant path. The boil-off gas is supplied to the fuel cell or the hydrogen engine through the boil-off gas supply path.

  A superconducting motor is composed of a coil made of a superconducting wire, and in order to place the coil in a superconducting state, it is necessary to cool the coil to a temperature at which the coil is in a superconducting state (referred to as “superconducting temperature”). When a part of the liquid fuel is supplied from the liquid fuel tank to the refrigerant circulation jacket as the cooling refrigerant, there is no need to provide a special cooling means, and the superconducting motor is cooled to the superconducting state. can do.

  Further, boil-off gas is likely to be generated when a part of the liquid fuel is circulated from the liquid fuel tank through the refrigerant path. In particular, the liquid fuel that is heated and used for cooling the superconducting motor is likely to be boil-off gas. Boil-off gas is generated on the return path. When flowing into the circulation path, boil-off gas is generated from the liquid fuel by cooling the superconducting motor. Therefore, when this boil-off gas is supplied to the fuel cell or the hydrogen engine through the boil-off gas supply path connected to the refrigerant path, the energy of the boil-off gas can be used effectively without waste.

In addition, when a superconducting motor is used as a driving motor, a higher torque can be realized as compared with a conventional motor, and smooth acceleration can be realized when starting a vehicle or traveling on a slope. In addition, a reduction gear is not required, copper loss due to motor rotation does not occur, and durability is excellent.
In addition, after the boil-off gas is used to generate power with the fuel cell or the hydrogen engine and the generator, the power charged in the secondary battery can be effectively used as the power of the superconducting motor.

The boil-off gas supply path joins the gas supply path from the liquid fuel tank to the fuel cell or the hydrogen engine, and is generated in the refrigerant path together with the boil-off gas generated in the liquid fuel tank via the gas supply path. Boil-off gas may be supplied to the fuel cell or the hydrogen engine.
With the above configuration, the boil-off gas processing mechanism is simply configured by supplying both the boil-off gas generated in the liquid fuel tank and the boil-off gas generated from the liquid fuel used as the refrigerant to the fuel cell or the hydrogen engine. be able to.

It is preferable to provide an on-off valve that opens and closes when the pressure in the boil-off gas supply path reaches a set value.
Specifically, a pressure sensor is provided in the boil-off gas supply path, and the flow path opening / closing valve is opened when the pressure detected by the pressure sensor reaches a set value, and the flow path is closed when the pressure falls below the set value. .
With the above configuration, when the boil-off gas is filled in the boil-off gas supply path, the flow path is opened and the boil-off gas is supplied to the fuel cell. In other words, the boil-off gas supply path can be degassed.

  The vehicle is equipped with a cooler that cools the liquid fuel in the liquid fuel tank, and when the vehicle is parked or stopped, power is supplied to the cooler from an external fixed power source to operate, and the liquid fuel in the liquid fuel tank is vaporized. It is preferable that the configuration is not allowed.

The liquid fuel in the liquid fuel tank is easily vaporized when the vehicle is parked or stopped, especially in hot weather such as in summer, but with the above configuration, the liquid fuel in the liquid fuel tank is cooled to prevent vaporization of the liquid fuel. Therefore, liquid fuel can always be used as a refrigerant for cooling equipment such as a superconducting motor. In addition, the boil-off gas vaporized by cooling a device such as a superconducting motor can be used as the fuel for the fuel cell or the fuel for the hydrogen engine, and the liquid fuel can be used efficiently.
Further, it is possible to prevent a risk that the pressure in the tank increases due to the vaporization of the liquid fuel.

It is preferable to use a cooler using a Peltier element or a compressor (compressor) attached to the liquid fuel tank as the cooler.
If the Peltier element is used as a cooler, the cooling mechanism can be simplified and the power consumption can be reduced.

It is preferable that power supply from the external fixed power source to the cooler is performed by induction power feeding in which the output unit of the external fixed power source and the input unit on the vehicle side are contactless.
For example, an external fixed power source is provided in a parking space such as a parking lot, and a primary coil that performs induction feeding is provided on the external fixed power source side, while a secondary coil is mounted on the vehicle side, and the vehicle is parked as described above. When a vehicle is parked in a required place in a space and an input unit on the vehicle side is disposed in close proximity to the output unit on the external fixed power source side, induction power is generated by the primary coil and the secondary coil, and power is supplied to the cooler. It is said.
With the above configuration, since the vehicle is not connected to the external fixed power source via an electric wire, no problem occurs even if the vehicle is started in a state where power is forgotten.

On the other hand, when power is supplied from the external fixed power source to the cooler via a power line, it is preferable from a safety point to provide a means for stopping the start of the vehicle in a connected state by the power line. .
For example, in a state of being connected via the power line, a detecting means for detecting the state is provided so that the vehicle engine is not started at the time of detection.
With the above configuration, it is possible to prevent the power line from being forcibly pulled out due to departure when power is supplied to the vehicle, and to prevent damage to the external fixed power source, the power line, and the power input unit on the vehicle side.

  The liquid fuel is limited to liquid hydrogen when supplying boil-off gas to a hydrogen engine, but when supplying boil-off gas to a fuel cell, carbon monoxide other than liquid hydrogen, hydrocarbons such as methane, etc. It may be a simple substance or compound that becomes a gas at normal temperature, enables a fuel cell reaction, and liquefies at a low temperature.

  As is clear from the above description, according to the present invention, boil-off gas generated in a vehicle equipped with liquid fuel is supplied to a fuel cell or a hydrogen engine, and the energy of the boil-off gas is also converted into electric energy to generate electric power. Therefore, the energy of the boil-off gas can be stored in the vehicle and used effectively. Therefore, it is not necessary to store the boil-off gas in the form of gas, and no pressurizing device or heating device is required, and the boil-off gas processing device can be reduced in size and weight. It can be used without waste as electric energy.

In addition, in the case of a vehicle using a superconducting motor using a superconducting coil, boil-off gas generated in the refrigerant path is also supplied to the fuel cell by using a part of the liquid fuel as a cooling refrigerant for the coil. Thus, an increase in gas pressure in the refrigerant path can be suppressed, and the energy of the boil-off gas can be supplied to the fuel cell and converted to electric energy for use without waste.
Furthermore, if the liquid fuel in the liquid fuel tank is cooled by a cooler operating with external fixed electric power so as not to be vaporized, it can be used as a refrigerant for cooling a device such as a superconducting motor, and the device is cooled. The boil-off gas thus vaporized can be supplied to the fuel cell or the hydrogen engine and reused as fuel, so that liquid fuel can be used efficiently.

A first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a fuel cell vehicle 20 on which a boil-off gas treatment system 10 is mounted. The fuel cell vehicle 20 is equipped with a superconducting motor 11 using a superconducting coil as power and a fuel cell 12 as a power source for the superconducting motor 11.

The fuel cell 12 is connected to a fuel gas supply path 13 for supplying hydrogen gas as a fuel from the liquid fuel tank 14.
The hydrogen stored as liquid hydrogen in the liquid fuel tank 14 is gasified in the fuel gas supply passage 13 and supplied to the fuel cell 12. The fuel cell 12 electrochemically combines hydrogen and oxygen in the air. Electric power is generated by reacting, and this electric power is supplied to the inverter 15 to convert a direct current into an alternating current to drive the superconducting motor 11.

  When the boil-off gas is generated in the liquid fuel tank 14 to generate boil-off gas and the pressure in the liquid fuel tank 14 reaches a set value or more, the boil-off gas is led out to the fuel gas supply path 13 to the fuel cell 12. Supply.

  The fuel cell vehicle 20 is equipped with a secondary battery 16 connected to the fuel cell 12, and when the electric power generated by the fuel cell 12 is generated more than the electric power supplied to the inverter 15 when the vehicle travels. Is supplied to the secondary battery 16 for charging and stored.

The superconducting motor 11 includes a coil made of a superconducting wire, and the coil is housed in a refrigerant circulation jacket 17 in a vacuum state with a voltmeter attached to both ends. A refrigerant path 18 is provided between the refrigerant circulation jacket 17 and the liquid fuel tank 14 to circulate a part of liquid hydrogen as a refrigerant.
The refrigerant path 18 includes a refrigerant flow path 18c in the refrigerant circulation jacket 17, a refrigerant forward path 18a for supplying liquid hydrogen from the liquid fuel tank 14 to the refrigerant flow path 18c of the refrigerant circulation jacket 17, and a liquid fuel from the refrigerant flow path 18c. The refrigerant return path 18 b returns to the tank 14. The pipes forming the refrigerant forward path 18a and the refrigerant return path 18b have a heat insulating material, and in particular, in the refrigerant forward path 18a, heat insulation is performed so that liquid hydrogen is not heated.

  The ultra-low temperature liquid hydrogen is circulated through the refrigerant forward path 18a subjected to the heat insulation of the refrigerant path 18 and is supplied to the refrigerant flow path 18c of the refrigerant circulation jacket 17, but a certain amount of boil-off gas is also generated during the circulation of the refrigerant forward path 18a. . Further, since liquid hydrogen heated by cooling of the superconducting motor is circulated through the refrigerant return path 18b, it contains a large amount of boil-off gas. In this way, since the boil-off gas is generated in the refrigerant forward path 18a and the refrigerant return path 18b, the boil-off gas supply path 19 is branched and connected to the fuel gas supply path 13 at its tip, and the fuel gas supply path The boil-off gas is supplied to the fuel cell 12 through 13.

  Channel open / close valves 20A and 20B are provided at positions where the boil-off gas supply path 19 communicates with the refrigerant forward path 18a and the refrigerant return path 18b, respectively, and pressure sensors 21A and 21B installed in the refrigerant forward path 18a and the refrigerant return path 18b are set values. If it becomes above, the said flow-path opening-and-closing valve 20A, 20B will be opened, and boil-off gas will be guide | induced to the boil-off gas supply path 19. FIG.

Next, a boil-off gas processing method by the boil-off gas processing system 10 having the above-described configuration will be described.
During travel of the fuel cell vehicle 20, liquid hydrogen is gasified from the liquid fuel tank 14 to the fuel gas supply path 13, supplied to the fuel cell 12, and generated by the fuel cell 12. The electricity generated by the fuel cell 12 is supplied to an inverter 15 that converts a direct current into an alternating current to drive the superconducting motor 11.

If the superconducting motor 11 continues to be driven to run the fuel cell vehicle 20, the superconducting coil of the superconducting motor 11 becomes high temperature.
For cooling the superconducting motor 11, a part of the liquefied hydrogen in the liquid fuel tank 14 passes through the refrigerant forward path 18a of the refrigerant path 18 and circulates through the refrigerant channel 18c in the refrigerant circulation jacket 17 of the superconducting motor 11 to be superconducting motor. 11 is cooled. Therefore, the superconducting temperature of the superconducting motor 11 can always be kept at the superconducting temperature without overheating even if the vehicle continues to travel.

The refrigerant circulated in the refrigerant circulation jacket 17 and cooled the superconducting motor 11 generates boil-off gas by heating, and this boil-off gas flows into the refrigerant return path 18b. Further, although not as much as the boil-off gas in the refrigerant return path 18b, boil-off gas is also generated in the refrigerant forward path 18a.
When the pressure rises due to the boil-off gas generated in the refrigerant forward path 18a and the refrigerant return path 18b and exceeds the set pressure, the on-off valves 20A and 20B are opened, and the boil-off gas is led out to the boil-off gas supply path 19.
The boil-off gas is introduced from the boil-off gas supply path 19 through the fuel gas supply path 13 into the fuel cell 12.

When the vehicle travels, the boil-off gas introduced from the boil-off gas supply path 19 is supplied to the fuel cell 12 together with the gas supplied from the liquid fuel tank 14, so that the electric power generated by the fuel cell 12 passes through the inverter 15. And used for driving the superconducting motor 11.
At that time, in addition to the vaporized hydrogen supplied directly from the hydrogen fuel tank, even when a large amount of hydrogen consisting of hydrogen in the boil-off gas is supplied to the fuel cell 12 from the boil-off gas supply path 19, all It is converted into electric energy and surplus power is supplied to the secondary battery 16.

  Further, even when the vehicle is not traveling, when the pressure in the refrigerant reciprocating paths 18a and 18b of the refrigerant path is increased by the boil-off gas, the on-off valves 20A and 20B are opened and the boil-off gas is supplied to the boil-off gas supply path 19. Derived and supplied to the fuel cell 12. The electric power generated by the power generation supplied to the fuel cell 12 is supplied to the secondary battery 16 and stored.

  The electric power stored in the secondary battery 16 can be used not only for driving the superconducting motor 11 but also for driving auxiliary devices other than the driving power supply as required.

  The boil-off gas supply path 19 is not connected to the fuel gas supply path 13 that connects the liquid fuel tank 14 and the fuel cell 12, but is directly introduced into the fuel cell 12 as shown by a two-dot chain line in FIG. It is good also as composition to do.

2 and 3 show a second embodiment of the present invention.
The present embodiment has substantially the same configuration as the first embodiment, but a cooler 30 is attached to the liquid fuel tank 14, and the liquid hydrogen in the liquid fuel tank 14 is cooled and vaporized by the cooler 30. This is different from the first embodiment in that it is prevented.
Electric power is supplied to the cooler 30 by inductive power feeding by a primary coil 32 connected to the external fixed power source 31 and a secondary coil 33 mounted on the vehicle and connected to the cooler 30.

The cooling machine 30 employs a cooling method using a Peltier element 34 shown in FIG.
That is, the heat absorption surface 34a of the Peltier element 34 is brought into contact with and adhered to the outer surface of the liquid fuel tank 14 storing liquid hydrogen, so that the liquid hydrogen in the liquid fuel tank 14 is cooled and not vaporized. .
The Peltier element 34 has a configuration in which thermoelectric elements 34c and 34d made of p-type and n-type semiconductors are arranged in parallel and connected in series to pass current, and ceramic plates 34e and 34f are attached to both sides. The Peltier element 34 is configured to generate a heat absorbing surface 34a and a heat radiating surface 34b by the Peltier effect when energized, and to cool the liquid hydrogen in the liquid fuel tank 14 in contact with the heat absorbing surface 34a.

  With the above configuration, since the liquid fuel in the liquid fuel tank 14 is cooled to prevent vaporization of the liquid fuel, the decrease in the liquid fuel can be suppressed, and the liquid fuel is always used as a refrigerant for cooling the superconducting motor 11. be able to. Further, the vapor pressure of the liquid fuel tank 14 can be suppressed from increasing as the liquid fuel is vaporized.

FIG. 4 shows a third embodiment of the present invention.
In the present embodiment, liquid hydrogen in the liquid fuel tank 14 is cooled by a cooler 40 using a compressor, and the cooler 40 can be connected to a household power source 42 via a power line 41. .

  Further, when the power line 41 is connected to the vehicle, a signal is sent from the sensor 43 that detects the connection state of the cooler 40 and the power line 41 to the control means 43 of the fuel cell 12 and the secondary battery 16, and the signal is received. During this time, power is not supplied from the fuel cell 12 and the secondary battery 16 to the superconducting motor 11. This prevents the vehicle from starting when the power line 41 is connected to the vehicle.

  FIG. 5 shows a fourth embodiment of the present invention, in which the cold head 51 protruding from the cooler 50 is directly inserted into the liquid fuel tank 14, and the cooled cold head 51 is converted into liquid hydrogen in the liquid fuel tank 51. It is cooled by contact.

With the above configuration, the liquid hydrogen can be efficiently cooled by bringing the cold head 51 of the cooler 50 into direct contact with the liquid hydrogen in the liquid fuel tank 14 for cooling.
In addition, since another structure and an effect are the same as that of 3rd Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 6 shows a fifth embodiment of the present invention. A vehicle according to the fifth embodiment uses a hydrogen engine and a generator operated by the hydrogen engine as an electric power generation device instead of a fuel cell.
The boil-off gas generated in the liquid hydrogen fuel tank 14 and the boil-off gas in the refrigerant passage 18 for supplying liquid hydrogen for cooling the superconducting motor 11 as in the first embodiment are supplied to the hydrogen engine 60, and the hydrogen engine The generator 61 is operated at 60, and the generated electric power is supplied to the superconducting motor 11 for driving. When the superconducting motor 11 is not driven, it is supplied to and stored in the secondary battery 16.

  In any of the first to fifth embodiments, the boil-off gas vaporized in the liquid fuel tank and the boil-off gas vaporized in the refrigerant path can be sent to the power generation device and reused as power generation energy. It is possible to suppress the pressure rise in the liquid fuel tank and effectively use the boil-off gas.

It is the schematic which shows the boil off gas processing system of 1st Embodiment of this invention. It is the schematic which shows the boil off gas processing system of 2nd Embodiment of this invention. It is the schematic of the Peltier device used for cooling of liquid hydrogen in 2nd Embodiment. It is the schematic which shows the boil off gas processing system of 3rd Embodiment of this invention. It is the schematic which shows the boil off gas processing system of 4th Embodiment of this invention. It is the schematic which shows the boil off gas processing system of 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Boil-off gas processing apparatus 11 Motor 12 Fuel cell 13 Fuel gas supply path 14 Liquid fuel tank 15 Inverter 16 Secondary battery 17 Refrigerant circulation jacket 18 Refrigerant path 18a Refrigerant forward path 18b Refrigerant return path 19 Boil-off gas supply path 20 Fuel cell vehicles 30, 40 50 Cooling machine 31 External fixed power supply 32 Primary coil 33 Secondary coil 34 Peltier element 42 Power supply 51 for home 51 Cold head 60 Hydrogen engine 61 Generator

Claims (10)

A processing system for boil-off gas generated from liquid fuel for a fuel cell mounted on a vehicle,
A boil-off gas generated in a refrigerant path for circulating liquid fuel from the liquid fuel tank as a refrigerant in a liquid fuel tank mounted on a vehicle and / or equipment other than the fuel cell is supplied to the fuel cell. A boil-off gas treatment system characterized by generating electricity through reaction. A processing system for boil-off gas generated from liquid fuel comprising liquid hydrogen mounted on a vehicle,
A boil-off gas made of gaseous hydrogen generated in a refrigerant path for circulating liquid hydrogen from the liquid hydrogen tank is supplied to the hydrogen engine inside the liquid hydrogen tank mounted on the vehicle and / or for the refrigerant of the equipment, and the hydrogen engine generates electric power. A boil-off gas processing system characterized by operating the machine.   The boil-off gas processing system according to claim 1 or 2, wherein surplus power generated by a generator operated by the fuel cell or the hydrogen engine is used for charging the secondary battery. A superconducting motor using a superconducting coil as the motor is used as the motor for driving the vehicle, and the superconducting motor is driven by power supplied from the fuel cell or power supplied from the generator. The motor is accommodated in a refrigerant circulation jacket, and a refrigerant path for circulating a part of the liquid fuel in the liquid fuel tank as a refrigerant is provided in the refrigerant circulation jacket and a boil-off gas supply path is branched and connected to the refrigerant path. , the boil through off gas supply channel of the mounting serial to any one of claims 1 to 3 supplies the BOG to a power generating apparatus consisting of the fuel cell or hydrogen engine boil-off gas treatment system.   The boil-off gas supply path joins the gas supply path from the liquid fuel tank to the fuel cell or the hydrogen engine, and is generated in the refrigerant path together with the boil-off gas generated in the liquid fuel tank via the gas supply path. The boil-off gas processing system according to any one of claims 1 to 4, wherein boil-off gas is supplied to the fuel cell or the hydrogen engine.   The boil-off gas processing system according to any one of claims 1 to 5, further comprising an on-off valve that opens and closes when the pressure in the refrigerant path reaches a set value.   The vehicle is equipped with a cooler that cools the liquid fuel in the liquid fuel tank, and when the vehicle is parked or stopped, power is supplied to the cooler from an external fixed power source to operate the liquid fuel in the liquid fuel tank. The boil-off gas processing system according to any one of claims 1 to 6, wherein the boil-off gas processing system is configured not to vaporize.   The boil-off gas processing system according to claim 7, wherein a Peltier element or a compressor attached to the liquid fuel tank is used as the cooler, and the Peltier element or the compressor is operated by the external fixed power source.   The power supply from the external fixed power source to the cooler is configured such that a dielectric power feeding mechanism is provided between the output portion of the external fixed power source and the power input portion of the cooler on the vehicle side to supply power without contact. The boil-off gas processing system according to claim 7 or 8.   The boil-off gas according to claim 7 or 8, wherein power is supplied from the external fixed power source to the cooler via a power line, and means for stopping the start of the vehicle in a connected state via the power line is provided. Processing system.

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