Ships

Abstract

A ship (20) comprises an LNG tank (1) that stores LNG, a device (2, 3) that separates hydrogen and carbon dioxide from the LNG stored in the LNG tank (1), a fuel cell (6) that generates power using the hydrogen separated by the device (2, 3), and a carbon dioxide storage tank (5) that stores the carbon dioxide separated by the device (2, 3).

Description

[Technical field]

[0001] The present invention relates to a marine vessel. [Background technology]

[0002] 2. Description of the Related Art Generally, ships that use LNG (liquefied natural gas) as fuel to generate electric power using a diesel generator are known (see, for example, Patent Document 1). However, burning LNG produces carbon dioxide, which has potential negative effects on the global environment and must be reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-192895 A Summary of the Invention

[0004] An object of an embodiment of the present invention is to provide a ship that generates electricity while reducing carbon dioxide emissions. A marine vessel according to an aspect of the present invention comprises a gas storage tank for storing liquid gas; a reforming reaction means for chemically decomposing the gas into hydrogen and carbon dioxide by a reforming reaction; The above A mixture containing hydrogen and carbon dioxide decomposed by a reforming reaction means. Separating hydrogen and carbon dioxide from gas Gas mixtures A separating means; a first heat exchange means for performing heat exchange so as to cool the mixed gas with hydrogen separated by the mixed gas separation means, a second heat exchange means for performing heat exchange so as to cool the mixed gas cooled by the first heat exchange means with air, and a cooling means for cooling the mixed gas cooled by the second heat exchange means and sent to the mixed gas separation means to a temperature equal to or lower than an allowable temperature of the mixed gas separation means; The above Heat exchange by the first heat exchange means Hydrogen and the air heat exchanged by the second heat exchange means A fuel cell that generates power by the Gas mixtures and a carbon dioxide storage tank for storing the carbon dioxide separated by the separation means. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a configuration diagram showing the configuration of a ship according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an overview of the flow of energy and materials in the ship according to this embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of a configuration for reusing hydrogen contained in water vapor discharged from the fuel cell according to this embodiment. [Figure 4] FIG. 4 is a configuration diagram showing an example of a configuration for cooling the mixed gas sent to the carbon dioxide separation device in this embodiment. [Diagram 5] FIG. 5 is a configuration diagram showing an example of the configuration of a carbon dioxide liquefaction device according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] (Embodiment) Fig. 1 is a configuration diagram showing the configuration of a ship 20 according to an embodiment of the present invention. Fig. 2 is a schematic diagram showing an overview of the flow of energy and materials in the ship 20 according to the embodiment. Note that the same parts in the drawings are given the same reference numerals, and duplicated explanations will be omitted as appropriate.

[0007] The ship 20 is a ship that generates power using LNG stored on board as fuel. The ship 20 may be any ship as long as it is equipped with facilities for storing LNG. For example, the ship 20 may be an LNG ship intended to transport LNG, a ship that uses LNG as fuel for a power source and intended to transport things other than LNG, or a ship that is not intended to transport things.

[0008] In this embodiment, LNG is used as the fuel for the fuel cell 6, but LPG (liquefied petroleum gas) may be used in the same manner as LNG. In addition, the fuel for the fuel cell 6 may be any substance containing hydrogen and carbon atoms. For example, such a fuel may be alcohol such as ethanol or methanol. Furthermore, substances not containing carbon atoms such as hydrogen or ammonia may be used as fuels other than the fuel cell 6, and these substances may be used as part of the fuel for the fuel cell 6.

[0009] The ship 20 is equipped with multiple LNG tanks 1, a reformer 2, a carbon dioxide separation device 3, a carbon dioxide liquefaction device 4, a carbon dioxide storage tank 5, a fuel cell 6, multiple solar cells 7, a storage battery 8, a distribution panel 9, a DC motor 10, a propulsion device 11, a steam turbine 12, and a condenser 13.

[0010] The LNG tank 1 is a facility for storing LNG. The LNG tank 1 supplies boil off gas (BOG) to the reformer 2 according to the amount of power demanded by the fuel cell 6. BOG is a gaseous natural gas that is generated when a portion of the LNG stored in the LNG tank 1 is vaporized by heat input.

[0011] The LNG tank 1 is a tank for storing LNG for transportation in the case of an LNG ship, but may be a fuel tank for storing LNG as fuel for a power source. Any number of LNG tanks 1 may be provided as long as they are one or more.

[0012] The reformer 2 is a device that adds high-temperature steam (for example, about 900°C) to the BOG supplied from the LNG tank 1, and chemically decomposes the BOG into mainly two components, hydrogen and carbon dioxide. For example, the reformer 2 uses steam discharged from the fuel cell 6 as the high-temperature steam. This steam may be heated by a heater before being supplied. The reformer 2 adds high-temperature steam to the LNG, and generates a reforming reaction (endothermic reaction) and a shift reaction, thereby generating a mixed gas of hydrogen and carbon dioxide. A reforming reaction occurs between methane (LNG) and steam, generating hydrogen and carbon monoxide. Furthermore, a shift reaction occurs between carbon monoxide and steam, generating hydrogen and carbon dioxide. As a result, the BOG is chemically decomposed into hydrogen and carbon dioxide. The reformer 2 supplies the generated mixed gas of hydrogen and carbon dioxide to the carbon dioxide separator 3.

[0013] The water vapor discharged from the fuel cell 6 contains hydrogen that did not react in the fuel cell 6. Therefore, by utilizing the water vapor discharged from the fuel cell 6, such unreacted hydrogen is reused via the reformer 2. Note that instead of utilizing the water vapor discharged from the fuel cell 6, a separate facility for supplying high-temperature water vapor to the reformer 2 may be provided.

[0014] Here, the mixed gas obtained after the decomposition of BOG may contain components other than hydrogen and carbon dioxide. For example, the mixed gas may contain BOG or carbon monoxide that has not been sufficiently decomposed, or impurities contained in BOG.

[0015] The carbon dioxide separation system (CCS) 3 physically separates the mixed gas of hydrogen and carbon dioxide chemically decomposed by the reformer 2 into carbon dioxide gas and hydrogen gas. For example, the carbon dioxide separation system 3 separates the mixed gas by pressure swing adsorption (PSA), but any method may be used to separate the mixed gas. After separating the mixed gas, the carbon dioxide separation system 3 supplies the hydrogen gas to the fuel cell 6 and sends the carbon dioxide gas to the carbon dioxide liquefaction system 4. A compressor C1 for compressing the hydrogen gas may be appropriately provided in a path (e.g., a pipeline) for sending the hydrogen gas from the carbon dioxide separation system 3 to the fuel cell 6.

[0016] The carbon dioxide liquefaction device 4 cools the carbon dioxide gas sent from the carbon dioxide separation device 3 to generate liquid carbon dioxide. The carbon dioxide liquefaction device 4 stores the liquefied carbon dioxide in the carbon dioxide storage tank 5. By storing the carbon dioxide in the carbon dioxide storage tank 5 in this manner, the emission of carbon dioxide while the ship 20 is sailing is suppressed.

[0017] The carbon dioxide storage tank 5 may be installed so as to be removable from the ship 20, or may be configured to be connected to a transport pump in order to send liquefied carbon dioxide outside the ship, or may be provided with both. The carbon dioxide storage tank 5 may also be provided with a loading pump in addition to the transport pump in order to extract the carbon dioxide stored in the carbon dioxide storage tank 5. In this way, the carbon dioxide stored in the carbon dioxide storage tank 5 can be carried to land and disposed of freely. The carbon dioxide stored in the carbon dioxide storage tank 5 may be disposed of by burying it in the ground, or may be used for applications that require carbon dioxide as a resource.

[0018] For example, the reformer 2, the carbon dioxide separation device 3, and the carbon dioxide liquefaction device 4 may be installed together in one building BD of the ship 20. This protects these devices 2 to 4 from external factors such as salt damage, and shortens the route (e.g., pipeline) for transporting substances (carbon dioxide, etc.). In addition, it is desirable for the carbon dioxide storage tank 5 to be installed near the carbon dioxide liquefaction device 4, at a location where the carbon dioxide stored therein can be easily unloaded.

[0019] The fuel cell 6 is a solid oxide fuel cell (SOFC) that generates power by using oxygen in the air taken in from the atmosphere and hydrogen gas supplied by the carbon dioxide separation device 3. The fuel cell 6 supplies the generated power to a DC motor 10 via a switchboard 9.

[0020] Furthermore, the fuel cell 6 may supply the generated electricity to electrical equipment on the ship other than the DC motor 10. Water vapor discharged from the fuel cell 6 and containing hydrogen that remains unreacted is sent to the reformer 2 and the steam turbine 12. Note that although the fuel cell 6 is described here as being of a solid oxide type, other types of fuel cells may also be used. The fuel cell 6 may also be installed inside a building to protect it from external factors such as salt damage.

[0021] The solar cell 7 is a battery that converts sunlight into electrical energy. The solar cell 7 is installed in a location on the surface side of the ship 20 where sunlight is irradiated (for example, a deck, etc.). The solar cell 7 supplies the generated power to the DC motor 10 via a switchboard 9. The solar cell 7 may also supply the generated power to electrical equipment on the ship other than the DC motor 10. The solar cell 7 does not have to be installed on the ship 20.

[0022] The storage battery 8 is connected to a switchboard 9. When the power demand to be supplied to the DC motor 10 and the like is greater than the power supplied from the fuel cell 6 and the solar cell 7, the storage battery 8 supplements the power supply with stored electrical energy. On the other hand, when the power demand is less than the power supplied from the fuel cell 6 and the solar cell 7, the storage battery 8 charges. In this way, the storage battery 8 charges and discharges to balance the power demand and the power supply. The storage battery 8 does not have to be provided on the ship 20.

[0023] Each of the fuel cell 6 and the solar cell 7 may include a control unit for controlling its own operation and a power converter for converting the output power to a desired power. Similarly, the storage battery 8 may include a control unit for controlling its own operation (charging, discharging, etc.) and a power converter for converting the charging / discharging power to a desired power.

[0024] The switchboard 9 is a device for supplying the power supplied from the fuel cell 6, the solar cell 7, and the storage battery 8 to the DC motor 10 and the like. When the storage battery 8 is charging, the switchboard 9 supplies the electric energy supplied from the fuel cell 6 and the solar cell 7 to the storage battery 8. Note that any number of switchboards 9 may be provided, and the switchboard 9 may be eliminated and a switch or the like provided instead.

[0025] The DC motor 10 is a power source for obtaining propulsive power for the boat 20. The DC motor 10 is driven by DC power supplied from the fuel cell 6, the solar cell 7, and the storage battery 8, so the number of power conversion circuits such as inverters can be reduced compared to when an AC motor is used, improving the overall energy efficiency of the boat 20. Note that an AC motor may be used instead of the DC motor 10.

[0026] The propulsion unit 11 is connected to the DC motor 10 and converts the rotational force of the DC motor 10 into propulsive force for the ship 20 .

[0027] The steam turbine 12 generates steam turbine power using the steam exhausted from the fuel cell 6. For example, the remaining steam, excluding the steam required for the reformer 2, from the steam exhausted from the fuel cell 6 is sent to the steam turbine 12. All of the steam exhausted from the fuel cell 6 may be sent to the steam turbine 12 and may not be sent to the reformer 2. The power generation by the steam turbine 12 may be used in any way. For example, the steam turbine 12 may supply the generated power to the switchboard 9. The steam exhausted from the fuel cell 6 may be sent directly to the condenser 13 without providing the steam turbine 12.

[0028] The condenser 13 is connected to the steam turbine 12. The condenser 13 converts the steam sent from the fuel cell 6 via the steam turbine 12 back into water, and extracts hydrogen contained in the steam. The condenser 13 supplies the hydrogen extracted from the steam to the fuel cell 6 as fuel. In this way, the hydrogen extracted from the condenser 13 is reused in the fuel cell 6. The water extracted from the condenser 13 may be reused or discarded. When discharging water from the condenser 13 to the outside, a condensate pump for discharging the water may be provided.

[0029] 3 is a diagram showing an example of a configuration for reusing hydrogen contained in water vapor discharged from the fuel cell 6 according to this embodiment. Note that the configuration is not limited to the one described here, and any other configuration may be used.

[0030] In a path (eg, a pipeline) that supplies hydrogen gas from the condenser 13 to the fuel cell 6, a vacuum pump P1 and a separator SP are provided.

[0031] The vacuum pump P1 is supplied with gas containing a large amount of hydrogen from the condenser 13. While maintaining the condenser 13 under vacuum, the vacuum pump P1 sends the gas containing a large amount of hydrogen supplied from the condenser 13 to the separator SP. The separator SP removes impurities other than hydrogen gas (water, carbon dioxide, etc.) from the gas supplied from the vacuum pump P1. In this way, the separator SP extracts highly pure hydrogen gas. The separator SP supplies the extracted hydrogen gas to the fuel cell 6. A compressor that compresses the hydrogen gas may be provided in the path along which the separator SP sends the hydrogen gas to the fuel cell 6.

[0032] FIG. 4 is a configuration diagram showing an example of a configuration for cooling the mixed gas sent to the carbon dioxide separator 3 in this embodiment.

[0033] The mixed gas of hydrogen and carbon dioxide discharged from the reformer 2 has a high temperature exceeding the allowable temperature of the carbon dioxide separator 3, and therefore cannot be fed to the carbon dioxide separator 3 without being cooled. Therefore, a cooler 31 for cooling the mixed gas is provided midway along the path (e.g., a pipeline) of the mixed gas fed from the reformer 2 to the carbon dioxide separator 3. Here, with reference to Fig. 4, a configuration in which two heat exchangers 32, 33 are provided in addition to the cooler 31 will be described.

[0034] The first heat exchanger 32 cools the mixed gas of hydrogen and carbon dioxide discharged from the reformer 2 by hydrogen gas supplied as fuel to the fuel cell 6 from the carbon dioxide separator 3 or the condenser 13. This cools the mixed gas and heats the hydrogen gas supplied as fuel to the fuel cell 6. Therefore, it is possible to cool the mixed gas and heat the hydrogen gas used as fuel for the fuel cell 6.

[0035] The second heat exchanger 33 cools the mixed gas cooled by the first heat exchanger 32 with oxygen (air) to be taken in as fuel by the fuel cell 6. This cools the mixed gas and heats the air to be taken in as fuel by the fuel cell 6. Therefore, it is possible to cool the mixed gas and heat the oxygen (air) to be used as fuel for the fuel cell 6.

[0036] The cooler 31 cools the mixed gas discharged from the reformer 2 and cooled in the two heat exchangers 32, 33 to a temperature equal to or lower than the allowable temperature of the carbon dioxide separation device 3. In this manner, the cooler 31 sends the mixed gas cooled to a temperature equal to or lower than the allowable temperature to the carbon dioxide separation device 3.

[0037] It should be noted that any number of coolers 31 may be provided. Also, any number of heat exchangers 32 and 33 may be provided, or they may not be provided at all. Furthermore, the order of cooling by the coolers and heat exchangers may be determined arbitrarily.

[0038] 5 is a configuration diagram showing an example of the configuration of the carbon dioxide liquefaction device 4 according to this embodiment. Note that the configuration of the carbon dioxide liquefaction device 4 described here is just one example, and any configuration may be used as long as it can liquefy carbon dioxide gas.

[0039] The carbon dioxide liquefaction device 4 includes a carbon dioxide compressor 41 , a dehumidification device 42 , a first heat exchanger 43 , a carbon dioxide liquefaction device 44 , a refrigerator 45 , a refrigerant condenser 46 , and a second heat exchanger 47 .

[0040] The carbon dioxide compressor 41 takes in and compresses the carbon dioxide gas separated by the carbon dioxide separator 3. The carbon dioxide compressor 41 sends the compressed carbon dioxide gas to the dehumidifier 42. The carbon dioxide compressor 41 may also take in carbon dioxide vaporized inside the carbon dioxide storage tank 5, in addition to the carbon dioxide gas from the carbon dioxide separator 3, and compress them together.

[0041] The dehumidifier 42 dries the carbon dioxide gas sent from the carbon dioxide compressor 41. This causes the purge gas to escape from the carbon dioxide gas. The dehumidifier 42 sends the dried carbon dioxide gas to the first heat exchanger 43. The dehumidifier 42 need not be provided.

[0042] The first heat exchanger 43 cools the carbon dioxide gas sent from the dehumidifier 42 with fresh water. The fresh water is cooling water that is prepared in advance on board the ship. Instead of fresh water, water (seawater, etc.) pumped from outside the ship by a water intake pump or the like may be used. The first heat exchanger 43 sends the cooled carbon dioxide gas to the carbon dioxide liquefier 44.

[0043] The carbon dioxide liquefier 44 cools and liquefies the carbon dioxide gas sent from the first heat exchanger 43. This causes non-condensable gas to escape from the carbon dioxide. The carbon dioxide liquefier 44 sends the liquefied carbon dioxide to the second heat exchanger 47.

[0044] The carbon dioxide liquefier 44 cools the carbon dioxide gas with a refrigerant. The refrigerant used to cool the carbon dioxide gas is sent to the refrigerator 45 and cooled. The refrigerant cooled in the refrigerator 45 is sent to the refrigerant condenser 46 and compressed. The refrigerant compressed in the refrigerant condenser 46 is supplied to the carbon dioxide liquefier 44 and used to cool the carbon dioxide gas.

[0045] The second heat exchanger 47 uses BOG to cool the liquefied carbon dioxide sent from the carbon dioxide liquefaction device 44. The second heat exchanger 47 cools the liquefied carbon dioxide and sends it to the carbon dioxide storage tank 5.

[0046] According to this embodiment, the following advantageous effects can be obtained. By separating BOG into hydrogen and carbon dioxide, removing the carbon dioxide, and supplying only the hydrogen as fuel to the fuel cell 6, it is easier to capture carbon dioxide than if BOG were directly supplied as fuel to the fuel cell 6. This makes it possible to reduce the amount of carbon dioxide emitted outside the ship.

[0047] By using the steam discharged from the fuel cell 6 as the high-temperature steam required to cause the reforming reaction in the reformer 2, the overall energy efficiency and equipment costs of the ship 20 can be reduced compared to providing a separate device for producing high-temperature steam. In addition, since the steam discharged from the fuel cell 6 contains hydrogen, the consumption efficiency of the hydrogen contained in the LNG can be improved.

[0048] By providing a condenser 13 and extracting hydrogen contained in the water vapor discharged from the fuel cell 6, the efficiency of consumption of hydrogen contained in the LNG can be improved.

[0049] By providing a steam turbine 12 in the path along which water vapor is discharged from the fuel cell 6 to the condenser 13, it is possible to generate electricity using the water vapor discharged from the fuel cell 6.

[0050] Heat exchangers 32 and 33 are provided to cool the mixed gas discharged from the reformer 2 using hydrogen supplied from the carbon dioxide separation device 3 to the fuel cell 6 and air to be used for power generation in the fuel cell 6. This allows the temperature of the mixed gas when cooling begins in the cooler 31 to be lower than when the mixed gas is cooled without providing the heat exchangers 32 and 33. Therefore, the mixed gas can be cooled efficiently, and a cooler 31 with a lower cooling capacity can be used. In addition, the hydrogen and air supplied to the fuel cell 6 are also heated, so the power generation efficiency of the fuel cell 6 can be improved.

[0051] In the carbon dioxide liquefaction device 4, the energy efficiency of cooling carbon dioxide can be improved by using BOG to cool carbon dioxide. In addition, the energy efficiency can be further improved by using water outside the ship, such as seawater, for cooling.

[0052] The present invention is not limited to the above-described embodiment, and components may be deleted, added, or modified. Furthermore, components of a plurality of embodiments may be combined or exchanged to create a new embodiment. Even if such an embodiment is directly different from the above-described embodiment, if the embodiment has the same gist as the present invention, the description thereof will be omitted, as it has been described as an embodiment of the present invention.

Claims

1. A gas storage tank for storing liquid gas; a reforming reaction means for chemically decomposing the gas into hydrogen and carbon dioxide by a reforming reaction; a mixed gas separation means for separating hydrogen and carbon dioxide from the mixed gas containing hydrogen and carbon dioxide decomposed by the reforming reaction means; a first heat exchange means for performing heat exchange so as to cool the mixed gas with hydrogen separated by the mixed gas separation means; a second heat exchange means for performing heat exchange so as to cool the mixed gas cooled by the first heat exchange means with air; a cooling means for cooling the mixed gas cooled by the second heat exchange means and sent to the mixed gas separation means to a temperature lower than an allowable temperature of the mixed gas separation means; a fuel cell that generates electricity using hydrogen that has been heat exchanged by the first heat exchange means and air that has been heat exchanged by the second heat exchange means; a carbon dioxide storage tank for storing the carbon dioxide separated by the mixed gas separation means; A ship comprising:

2. The reforming reaction means causes the reforming reaction by utilizing water vapor discharged from the fuel cell.

2. The watercraft according to claim 1 .

3. A hydrogen extraction means for extracting hydrogen contained in the water vapor discharged from the fuel cell.

2. The watercraft according to claim 1, further comprising:

4. A carbon dioxide liquefaction means for liquefying the carbon dioxide separated by the mixed gas separation means using boil off gas (BOG) generated in the gas storage tank for storage in the carbon dioxide storage tank.

2. The watercraft according to claim 1, further comprising:

5. A carbon dioxide liquefaction means for liquefying the carbon dioxide separated by the mixed gas separation means using water outside the ship for storage in the carbon dioxide storage tank.

2. The watercraft according to claim 1, further comprising:

6. A motor that obtains propulsive power for the ship using the power generated by the fuel cell.

2. The watercraft according to claim 1, further comprising:

7. The motor includes a DC motor driven by DC power.

7. The watercraft according to claim 6,

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