Carbon dioxide recovery system, vessel, and carbon dioxide recovery method

Abstract

This carbon dioxide recovery system is provided with: a carbon dioxide recovery unit that recovers gaseous carbon dioxide from a carbon dioxide-containing gas; a liquefaction unit that liquefies the gaseous carbon dioxide recovered by the carbon dioxide recovery unit; a plurality of storage units that can store liquefied carbon dioxide obtained through liquefaction by the liquefaction unit; a switching unit that sends the liquefied carbon dioxide obtained through liquefaction by the liquefaction unit while a part of the plurality of storage units are dispensing the liquefied carbon dioxide, into another storage unit, among the plurality of storage units, which have not dispensed the liquefied carbon dioxide; and a measuring unit that measures the liquefied carbon dioxide dispensed from the storage unit.

Description

Carbon dioxide capture system, ship, and carbon dioxide capture method

[0001] This disclosure relates to a carbon dioxide capture system, a ship, and a carbon dioxide capture method. This application claims priority to Japanese Patent Application No. 2023-144666, filed on September 6, 2023, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a ship (liquefied carbon dioxide transport ship) equipped with a tank (LCD container) for storing liquefied carbon dioxide (LCD) and a pump (cargo discharge pump, booster pump) for discharging the liquefied carbon dioxide from the container. After arriving at a destination, such a ship unloads the liquefied carbon dioxide by discharging the liquefied carbon dioxide from the tank using the pump.

[0003] JP 2010-266068 A

[0004] Meanwhile, in ships and the like, in order to reduce greenhouse gas emissions, carbon dioxide is sometimes captured from exhaust gas generated when burning fuel, for example. The gaseous carbon dioxide thus captured from the exhaust gas may be liquefied and stored in a tank in consideration of storage space. Generally, the amount of liquefied gas discharged from a tank is measured using a level gauge that measures the liquid level in the tank. However, in ships and the like as described above, even while the liquefied carbon dioxide in the tank is being discharged, carbon dioxide may be captured from the exhaust gas, causing the liquefied carbon dioxide to flow into the tank. This makes it difficult to measure the amount of liquefied carbon dioxide dispensed from the tank with high accuracy.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a carbon dioxide capture system, a ship, and a carbon dioxide capture method that can measure liquefied carbon dioxide dispensed from a storage section with greater accuracy.

[0006] In order to solve the above problems, the carbon dioxide capture system according to the present disclosure comprises a carbon dioxide capture unit, a liquefaction unit, multiple storage units, a switching unit, and a metering unit. The carbon dioxide capture unit captures gaseous carbon dioxide from a carbon dioxide-containing gas. The liquefaction unit liquefies the gaseous carbon dioxide captured by the carbon dioxide capture unit. The multiple storage units are capable of storing the liquefied carbon dioxide liquefied by the liquefaction unit. When some of the multiple storage units are dispensing liquefied carbon dioxide, the switching unit sends the liquefied carbon dioxide liquefied in the liquefaction unit to other of the multiple storage units that are not dispensing liquefied carbon dioxide. The metering unit measures the liquefied carbon dioxide dispensed from the storage units.

[0007] A vessel according to the present disclosure includes a hull and a carbon dioxide metering system as described above.

[0008] The carbon dioxide capture method of the present disclosure includes the steps of: sending liquefied carbon dioxide to one of a plurality of storage sections capable of storing liquefied carbon dioxide that is not dispensing liquefied carbon dioxide when one of the storage sections is dispensing liquefied carbon dioxide; sending liquefied carbon dioxide to one of the plurality of storage sections after stopping the dispensing of liquefied carbon dioxide from some of the storage sections; and weighing the liquefied carbon dioxide sent to the other storage sections while liquefied carbon dioxide is being dispensed from some of the storage sections after stopping the dispensing of liquefied carbon dioxide from some of the storage sections.

[0009] According to the carbon dioxide capture system, ship, and carbon dioxide capture method disclosed herein, the liquefied carbon dioxide discharged from the storage section can be measured with greater accuracy.

[0010] 1 is a side view of a ship according to a first embodiment of the present disclosure. FIG. 2 is a diagram illustrating the configuration of a carbon dioxide metering system according to a first embodiment of the present disclosure. FIG. 3 is a diagram illustrating a state in which a collection tank is dispensing liquefied carbon dioxide in a carbon dioxide metering system according to a first embodiment of the present disclosure. FIG. 4 is a diagram illustrating the hardware configuration of a calculation device provided in a ship according to an embodiment of the present disclosure. FIG. 5 is a functional block diagram of a calculation device provided in a ship according to an embodiment of the present disclosure. FIG. 6 is a flowchart illustrating the steps of a carbon dioxide metering method according to the first embodiment of the present disclosure. FIG. 7 is a side view of a ship according to a second embodiment of the present disclosure. FIG. 8 is a diagram illustrating the configuration of a carbon dioxide metering system according to a second embodiment of the present disclosure. FIG. 9 is a diagram illustrating a state in which a first collection tank is dispensing liquefied carbon dioxide in a carbon dioxide metering system according to a second embodiment of the present disclosure. FIG. 10 is a diagram illustrating a state in which a second collection tank is dispensing liquefied carbon dioxide in a carbon dioxide metering system according to a second embodiment of the present disclosure. A figure showing a state in which the second storage compartment is dispensing liquefied carbon dioxide in a carbon dioxide metering system related to a modified example of the second embodiment of the present disclosure.

[0011] First Embodiment A carbon dioxide capture system, a ship, and a carbon dioxide capture method according to an embodiment of the present disclosure will now be described with reference to Figures 1 to 15. (Overall configuration of ship) As shown in Figure 1, a ship 1A according to this embodiment includes at least a hull 2, a combustion device 8, and a carbon dioxide capture system 20A (see Figure 2).

[0012] (Hull Structure) The hull 2 ​​has a pair of side walls 3A, 3B that form its outer shell, a bottom wall 4, and an upper deck 5. The side walls 3A, 3B are made up of a pair of side wall shell plates that form the port and starboard sides, respectively. The bottom wall 4 is made up of a bottom wall shell plate that connects the side walls 3A, 3B. The upper deck 5 is a full-length deck that is exposed to the outside. The hull 2 ​​has a superstructure 6 with accommodation areas formed on the upper deck 5, for example, on the stern 2b side.

[0013] The hull 2 ​​illustrated in this embodiment has a cargo carrying section (hold) 7 closer to the bow 2a than the superstructure 6. Furthermore, this cargo carrying section 7 is provided with a plurality of cargo tanks 11. Note that although the example has been given in which a plurality of cargo tanks 11 are provided in the cargo carrying section 7, the present invention is not limited to this configuration, and for example, various types of cargo, such as containers, may be loaded in the cargo carrying section 7. Furthermore, although the example has been given in which the hull 2 ​​has a cargo carrying section 7, the present invention is not limited to a hull 2 ​​having a cargo carrying section 7.

[0014] The combustion device 8 is a device that generates thermal energy by burning fuel, and is provided inside the hull 2. Examples of the combustion device 8 include an internal combustion engine used as a main engine for propelling the ship 1A, an internal combustion engine used in a power generation facility that supplies electricity to the ship, and a boiler that generates steam as a working fluid. The combustion device 8 is connected to a fuel tank 9 provided inside the hull 2 ​​via a fuel supply piping system 101. The combustion device 8 combusts fuel supplied from the fuel tank 9 via the fuel supply piping system 101.

[0015] (Configuration of Carbon Dioxide Capture System) Fig. 2 is a diagram showing the configuration of a carbon dioxide capture system according to an embodiment of the present disclosure. As shown in Fig. 2, the carbon dioxide capture system 20A includes a carbon dioxide capture unit 23, a liquefaction unit 25, a plurality of storage units 21, a switching unit 27, and a metering unit 80.

[0016] (Configuration of Carbon Dioxide Capture Unit) The carbon dioxide capture unit 23 is provided in the hull 2, and captures gaseous carbon dioxide from the exhaust gas of the combustion device 8, which is a carbon dioxide-containing gas. In this embodiment, the carbon dioxide capture unit 23 is provided on the upper deck 5 of the hull 2, but the location of the carbon dioxide capture unit 23 is not limited to on the upper deck 5.

[0017] The carbon dioxide capture unit 23 captures carbon dioxide (gas) contained in the exhaust gas sent from the combustion device 8 (see FIG. 1) through the exhaust gas pipe 102. Examples of methods for capturing carbon dioxide include a chemical absorption method in which carbon dioxide is absorbed in an absorbing liquid. Furthermore, an example of an absorbing liquid when carbon dioxide is absorbed by a chemical absorption method is monoethanolamine (MEA). The carbon dioxide capture unit 23 separates the carbon dioxide absorbed in the absorbing liquid in a gaseous state from the absorbing liquid by, for example, heating the absorbing liquid that has absorbed carbon dioxide. This separated gaseous carbon dioxide is sent to the liquefaction unit 25. Here, the exhaust gas after the carbon dioxide has been absorbed in the absorbing liquid is subjected to, for example, a cleaning process and then released into the atmosphere through an exhaust funnel (not shown) or the like provided on the ship 1A.

[0018] (Configuration of Liquefaction Unit) The liquefaction unit 25 liquefies the gaseous carbon dioxide recovered by the carbon dioxide recovery unit 23. In this embodiment, the carbon dioxide recovery unit 23 and the liquefaction unit 25 are connected by the discharge piping system 105, and the liquefaction unit 25 liquefies the gaseous carbon dioxide sent from the carbon dioxide recovery unit 23 through the discharge piping system 105. More specifically, the liquefaction unit 25 compresses the gaseous carbon dioxide sent through the discharge piping system 105 and liquefies the compressed gaseous carbon dioxide by cooling it.

[0019] (Configuration of Storage Section) In this embodiment, the plurality of storage sections 21 include a collection tank 22 and a buffer tank 24 .

[0020] The recovery tank 22 is capable of storing carbon dioxide liquefied in the liquefaction section 25 (hereinafter referred to as liquefied carbon dioxide). The recovery tank 22 is a storage section 21A among the multiple storage sections 21. The recovery tank 22 illustrated in this embodiment is provided on the upper deck 5. The location of the recovery tank 22 is not limited to being on the upper deck 5, and it may be located, for example, below the upper deck 5. Note that while this embodiment illustrates an example in which one recovery tank 22 is provided, the number of recovery tanks 22 is not limited to one and may be multiple. Furthermore, while this embodiment illustrates an example in which the recovery tank 22 is a so-called horizontally placed cylindrical tank, the shape of the recovery tank 22 is not limited to any particular shape and may be, for example, spherical, rectangular, or the like.

[0021] The recovery tank 22 is connected to the liquefaction unit 25 via a transfer piping system 103. The transfer piping system 103 sends the liquefied carbon dioxide liquefied in the liquefaction unit 25 to the recovery tank 22. A pump (not shown) is provided in the transfer piping system 103 to pressure-feed the liquefied carbon dioxide to the recovery tank 22. Note that the pump may be omitted if the positional relationship and pressure difference between the liquefaction unit 25 and the storage unit 21 allow the liquefied carbon dioxide to be transferred from the liquefaction unit 25 to the storage unit 21. The transfer piping system 103 exemplified in this embodiment penetrates the top of the recovery tank 22 and extends to and opens at the bottom of the recovery tank 22, but is not limited to this configuration and may have any configuration as long as it is capable of sending the liquefied carbon dioxide liquefied in the liquefaction unit 25 to the recovery tank 22.

[0022] The buffer tank 24 is provided midway through the transfer piping system 103. The buffer tank 24 is capable of temporarily storing the liquefied carbon dioxide liquefied by the liquefaction unit 25. The liquefied carbon dioxide liquefied by the liquefaction unit 25 can be temporarily stored in the buffer tank 24 and then sent to the recovery tank 22. The buffer tank 24 is another storage unit 21B that is different from the storage unit 21A (recovery tank 22), which is one of the multiple storage units 21. The buffer tank 24 has a smaller capacity than the recovery tank 22.

[0023] A discharge piping system 104 is connected to the recovery tank 22. The discharge piping system 104 connects the recovery tank 22 to a manifold (not shown) provided on the hull 2. The manifold can be connected to an external piping system (not shown) for sending the liquefied carbon dioxide in the recovery tank 22 outside the ship. The discharge piping system 104 extends upward from the lower part of the recovery tank 22, penetrates the top of the recovery tank 22, and extends toward the manifold provided outside the recovery tank 22. A discharge pump 108 is provided at the tip of the discharge piping system 104 located at the lower part of the recovery tank 22. This discharge pump 108 is capable of pumping the liquefied carbon dioxide in the recovery tank 22 out of the recovery tank 22. The discharge piping system 104 pumps the liquefied carbon dioxide pumped by the lift pump 108 outside the ship via the manifold (not shown).

[0024] (Configuration of switching unit) The switching unit 27 is provided in the transfer piping system 103, between the buffer tank 24 and the recovery tank 22. The switching unit 27 is capable of interrupting the supply of liquefied carbon dioxide to the recovery tank 22 via the transfer piping system 103. The switching unit 27 exemplified in this embodiment is an on-off valve 27v. The on-off valve 27v opens and closes a flow path in the transfer piping system 103, thereby interrupting the supply of liquefied carbon dioxide to the recovery tank 22 via the transfer piping system 103.

[0025] When the on-off valve 27v is opened, the buffer tank 24 and the recovery tank 22 are connected via the transfer piping system 103, and the liquefied carbon dioxide liquefied in the liquefaction section 25 is sent to the recovery tank 22 via the buffer tank 24.

[0026] Fig. 3 is a diagram showing a state in which the recovery tank is discharging liquefied carbon dioxide. As shown in Fig. 3, when the on-off valve 27v is closed, communication between the buffer tank 24 and the recovery tank 22 via the transfer piping system 103 is blocked. As a result, after the on-off valve 27v is closed, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is blocked from being sent to the recovery tank 22, and is stored in the buffer tank 24.

[0027] The on-off valve 27v is open except when the recovery tank 22 is discharging liquefied carbon dioxide. In other words, while the ship 1A is sailing or at anchor, when the recovery tank 22 is not discharging liquefied carbon dioxide, the liquefied carbon dioxide liquefied by the liquefaction unit 25 is sent to and stored in the recovery tank 22. On the other hand, the on-off valve 27v is closed when the recovery tank 22 is discharging liquefied carbon dioxide. In other words, when the recovery tank 22, which is one of the storage units 21A among the multiple storage units 21, is discharging liquefied carbon dioxide, the liquefied carbon dioxide liquefied by the liquefaction unit 25 is stored in the buffer tank 24, which is the other storage unit 21B among the multiple storage units 21 that is not discharging liquefied carbon dioxide.

[0028] 2 , the metering unit 80 measures the liquefied carbon dioxide dispensed from the storage unit 21. The metering unit 80 of this embodiment includes a level meter 81, a thermometer 82, a pressure meter 83, a flow meter 92, a purity detector 87, a fuel meter 88, a fuel thermometer 84, and a computing device 50.

[0029] A level gauge 81, a thermometer 82, and a pressure gauge 83 are provided in the recovery tank 22. The level gauge 81 detects the liquid level in the recovery tank 22. The thermometer 82 detects the temperature of the liquefied carbon dioxide in the recovery tank 22. The pressure gauge 83 detects the pressure in the recovery tank 22 (gas phase pressure).

[0030] The flow meter 92 is provided in the discharge piping system 104. The flow meter 92 detects the flow rate of the liquefied carbon dioxide discharged from the recovery tank 22 by the discharge piping system 104. As the flow meter 92, a volumetric flow meter capable of detecting the volumetric flow rate of the liquefied carbon dioxide discharged from the recovery tank 22 by the discharge piping system 104 can be used.

[0031] The purity detector 87 is provided in the discharge piping system 104. The purity detector 87 detects the purity of the liquefied carbon dioxide discharged from the recovery tank 22 via the discharge piping system 104.

[0032] The fuel meter 88 is provided in the fuel supply piping system 101. The fuel meter 88 detects the flow rate of fuel supplied from the fuel tank 9 to the combustion device 8 via the fuel supply piping system 101. The fuel meter 88 can detect the amount of fuel consumed by the combustion device 8. In addition, the fuel thermometer 84 is provided in the fuel supply piping system 101. The fuel thermometer 84 detects the temperature of the fuel supplied from the fuel tank 9 to the combustion device 8 via the fuel supply piping system 101.

[0033] (Hardware Configuration Diagram) Fig. 4 is a diagram showing the hardware configuration of a computing device according to an embodiment of the present disclosure. As shown in Fig. 4, the computing device 50 is a computer including a CPU (Central Processing Unit) 51, a ROM (Read Only Memory) 52, a RAM (Random Access Memory) 53, a storage 54, and a signal transmission / reception module 55. The signal transmission / reception module 55 receives detection signals from a level gauge 81, a thermometer 82, a pressure gauge 83, a flow meter 92, a purity detector 87, a fuel gauge 88, and a fuel temperature gauge 84.

[0034] (Functional Block Diagram) Fig. 5 is a functional block diagram of a control device according to an embodiment of the present disclosure. As shown in Fig. 5, a CPU 51 of a calculation device 50 executes a program stored in advance in a storage device such as a ROM 52 or a storage 54, thereby realizing the functional configurations of a signal input unit 70, an information acquisition unit 71, a payout amount acquisition unit 72, and an information output unit 73.

[0035] The signal input unit 70 receives detection signals from each of the level gauge 81 , the temperature gauge 82 , the pressure gauge 83 , the flow meter 92 , the purity detector 87 , the fuel gauge 88 , and the fuel temperature gauge 84 via the signal transmitting / receiving module 55 .

[0036] Based on the detection signal received by the signal input unit 70, the information acquisition unit 71 acquires the detection values ​​of each parameter detected by each of the level meter 81, thermometer 82, pressure meter 83, flow meter 92, purity detector 87, fuel meter 88, and fuel thermometer 84.

[0037] The dispensing amount acquisition unit 72 acquires the mass of liquefied carbon dioxide dispensed from the recovery tank 22 based on the detection values ​​of each parameter detected by each of the level meter 81, thermometer 82, pressure meter 83, flow meter 92, and purity detector 87, which are acquired by the information acquisition unit 71. Note that although the dispensing amount acquisition unit 72 of this embodiment acquires the mass of liquefied carbon dioxide dispensed from the recovery tank 22, it may also acquire the volume of liquefied carbon dioxide dispensed from the recovery tank 22.

[0038] The dispensing amount acquisition unit 72 first obtains the mass of liquefied carbon dioxide dispensed from the collection tank 22 based on the detection results of the level meter 81, the thermometer 82, the pressure meter 83, and the purity detector 87. As shown in Fig. 2, the dispensing amount acquisition unit 72 acquires the detected value of the liquid level L1 by the level meter 81 before dispensing the liquefied carbon dioxide from the collection tank 22. Furthermore, as shown in Fig. 3, the dispensing amount acquisition unit 72 acquires the detected value of the liquid level L2 by the level meter 81 even while the liquefied carbon dioxide is being dispensed from the collection tank 22. Note that the dispensing of the liquefied carbon dioxide from the collection tank 22 continues until the liquid level L2 reaches a predetermined threshold, and stops (dispensing is completed) when the predetermined threshold is reached.

[0039] Furthermore, the dispensing amount acquisition unit 72 calculates the specific gravity of the liquefied carbon dioxide in the storage unit 21 based on the temperature of the liquefied carbon dioxide in the storage unit 21 detected by the thermometer 82 and the pressure in the storage unit 21 detected by the pressure gauge 83 before the liquefied carbon dioxide is dispensed from the storage unit 21 and after the liquefied carbon dioxide has been dispensed from the storage unit 21. Furthermore, the dispensing amount acquisition unit 72 calculates the mass of the liquefied carbon dioxide before the liquefied carbon dioxide is dispensed from the storage unit 21 based on the liquid level L1 before the liquefied carbon dioxide is dispensed from the storage unit 21 and the specific gravity of the liquefied carbon dioxide. Furthermore, the dispensing amount acquisition unit 72 calculates the mass of the liquefied carbon dioxide after the dispensing of the liquefied carbon dioxide from the storage unit 21 is completed based on the liquid level L2 after the dispensing of the liquefied carbon dioxide from the storage unit 21 is completed and the specific gravity of the liquefied carbon dioxide. The dispensing amount acquiring unit 72 then calculates the difference between the mass of the liquefied carbon dioxide before it is dispensed from the storage unit 21 and the mass of the liquefied carbon dioxide after the dispensing of the liquefied carbon dioxide from the storage unit 21 is completed. In this way, the dispensing amount acquiring unit 72 acquires the amount of change in the mass of the liquefied carbon dioxide stored in the storage unit 21 before the liquefied carbon dioxide is dispensed from the storage unit 21 and after the dispensing is completed. Note that the dispensing amount acquiring unit 72 may, for example, detect the temperature of the liquefied carbon dioxide in the collection tank 22 detected by the thermometer 82, the pressure in the collection tank 22 detected by the pressure gauge 83, and the purity of the liquefied carbon dioxide in the collection tank 22 detected by the purity detector 87 multiple times while the liquefied carbon dioxide is being dispensed from the collection tank 22, and use the average values ​​thereof to calculate the specific gravity of the liquefied carbon dioxide in the collection tank 22.

[0040] Here, the discharge amount acquisition unit 72 of the present embodiment acquires an integrated value of the flow rate of liquefied carbon dioxide discharged from the recovery tank 22 via the discharge piping system 104 based on the detection result of the flow meter 92, and acquires the amount of liquefied carbon dioxide discharged via the discharge piping system 104. The discharge amount acquisition unit 72 can also compare the flow rate of liquefied carbon dioxide acquired based on the detection result of the flow meter 92 with the discharge amount of liquefied carbon dioxide acquired based on the detection results of the level meter 81, thermometer 82, and pressure meter 83 as described above. This makes it possible to detect the occurrence of an abnormality with a simple configuration, for example, when an abnormality occurs in at least one of the level meter 81, thermometer 82, and pressure meter 83.

[0041] Furthermore, the discharge amount acquisition unit 72 of this embodiment acquires the mass of carbon dioxide in the gas discharged from the combustion device 8 based on the amount of fuel consumed detected by the fuel meter 88. More specifically, the discharge amount acquisition unit 72 calculates the weight consumption of fuel based on the amount of fuel consumed detected by the fuel meter 88, the temperature of the fuel detected by the fuel thermometer 84, and the bunker properties (specific gravity, viscosity, calorific value, etc. of the fuel) of the fuel loaded in the fuel tank 9. Note that information on the bunker properties of the fuel loaded in the fuel tank 9 is available in advance from the manufacturer, etc.

[0042] The discharge amount acquisition unit 72 calculates the amount (mass) of carbon dioxide emitted by burning fuel during navigation based on the calculated weight consumption of fuel and the carbon dioxide conversion factor specified by the IMO (International Maritime Organization).The discharge amount acquisition unit 72 of this embodiment then calculates the greenhouse gas (GHG: Green House Gas) reduction rate based on the difference between the mass of carbon dioxide emitted by burning fuel during navigation and the mass of the liquefied carbon dioxide discharged from the recovery tank 22.

[0043] The information output unit 73 outputs to the outside information based on the calculation results acquired by the dispensing amount acquisition unit 72 as described above. Examples of information output to the outside from the information output unit 73 include the mass of liquefied carbon dioxide dispensed from the recovery tank 22 and the greenhouse gas (GHG) reduction rate. Examples of output by the information output unit 73 include displaying an image on a monitor device, sending data to an external computer terminal, printing a document on a printer, etc.

[0044] (Procedure of Carbon Dioxide Capture Method) Figure 6 is a flowchart showing the procedure of a carbon dioxide capture method according to an embodiment of the present disclosure. As shown in Figure 6, a carbon dioxide capture method S10 according to an embodiment of the present disclosure includes a step S11 of blocking transfer of liquefied carbon dioxide from the buffer tank 24 to the capture tank 22, a step S12 of discharging the liquefied carbon dioxide, a step S12s of feeding liquefied carbon dioxide into the buffer tank 24, a step S13 of measuring the dispensed liquefied carbon dioxide, a step S14 of feeding the liquefied carbon dioxide into the capture tank 22 after stopping the dispense of liquefied carbon dioxide, a step S15 of discharging the liquefied carbon dioxide, a step S15s of feeding liquefied carbon dioxide into the buffer tank 24, and a step S16 of measuring the dispensed liquefied carbon dioxide.

[0045] Steps S11 to S13 shown below are performed the first time liquefied carbon dioxide is dispensed from the recovery tank 22 after the start of use of the carbon dioxide capture system 20A. After the start of use of the carbon dioxide capture system 20A, the on-off valve 27v is opened in the switching unit 27, as shown in FIG. 2. Carbon dioxide contained in the exhaust gas from the combustion device 8 is recovered in the carbon dioxide capture unit 23, and then liquefied in the liquefaction unit 25. The liquefied carbon dioxide liquefied in the liquefaction unit 25 is sent to the recovery tank 22 via the transfer piping system 103 and the buffer tank 24. As a result, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the recovery tank 22.

[0046] When the ship 1A arrives at a port or the like, the recovery tank 22 dispenses the liquefied carbon dioxide stored in the recovery tank 22. To do this, first, in step S11, which blocks the transfer of liquefied carbon dioxide from the buffer tank 24 to the recovery tank 22, the switching unit 27 closes the on-off valve 27v. This blocks the transfer of liquefied carbon dioxide from the buffer tank 24 to the recovery tank 22. Then, the process moves to step S12, which blocks the transfer of liquefied carbon dioxide from the buffer tank 24 to the recovery tank 22, and starts the dispense of the liquefied carbon dioxide stored in the recovery tank 22. In this step S12, the on-off valve 27v is closed and the transfer of liquefied carbon dioxide from the buffer tank 24 to the recovery tank 22 is blocked, so only the liquefied carbon dioxide stored in the recovery tank 22 is dispensed.

[0047] Step S12s of sending liquefied carbon dioxide to buffer tank 24 is carried out while liquefied carbon dioxide is being dispensed from recovery tank 22 in step S12. Step S12s is actually started at the same time as opening / closing valve 27v is closed in step S11. In step S12s, after opening / closing valve 27v is closed, the liquefied carbon dioxide liquefied in liquefaction section 25 is stored in buffer tank 24. When dispense of liquefied carbon dioxide from recovery tank 22 is completed in step S12, the dispense of liquefied carbon dioxide is stopped.

[0048] In step S13 of measuring the dispensed liquefied carbon dioxide, the liquefied carbon dioxide dispensed by the recovery tank 22 is measured. In step S13, the dispensed amount acquisition unit 72 detects the liquid level L1 in the recovery tank 22 on the level meter 81 immediately before starting to dispense the liquefied carbon dioxide from the recovery tank 22. Also, as shown in Fig. 3 , the dispensed amount acquisition unit 72 detects the liquid level L2 in the recovery tank 22 on the level meter 81 while the liquefied carbon dioxide is being dispensed from the recovery tank 22.

[0049] Furthermore, in step S13, the dispensing amount acquisition unit 72 acquires the temperature of the liquefied carbon dioxide in the recovery tank 22 detected by the thermometer 82 at each of the liquid level levels L1 and L2, the pressure in the recovery tank 22 detected by the pressure gauge 83, and the purity of the liquefied carbon dioxide in the recovery tank 22 detected by the purity detector 87. The dispensing amount acquisition unit 72 calculates the specific gravity of the liquefied carbon dioxide at each of the liquid level levels L1 and L2 in the recovery tank 22 based on the temperature of the liquefied carbon dioxide in the recovery tank 22 detected by the thermometer 82 at each of the liquid level levels L1 and L2, the pressure in the recovery tank 22 detected by the pressure gauge 83, and the purity of the liquefied carbon dioxide in the recovery tank 22 detected by the purity detector 87. The dispensing amount acquisition unit 72 accumulates the liquid level L1 before dispensing, the liquid level L2 at the completion of dispensing, and the specific gravity of the liquefied carbon dioxide at each liquid level L1 and L2 in the recovery tank 22, and calculates the difference to obtain the change in the mass of the liquefied carbon dioxide in the recovery tank 22.

[0050] Here, in this embodiment, while the liquefied carbon dioxide is being dispensed from the recovery tank 22, the flow meter 92 detects the flow rate of the liquefied carbon dioxide dispensed from the recovery tank 22 via the dispensing piping system 104. The dispensed amount acquisition unit 72 may acquire the amount of liquefied carbon dioxide dispensed via the dispensing piping system 104 based on the detection result of the flow meter 92, and compare the amount of liquefied carbon dioxide acquired based on the detection result of the flow meter 92 with the dispensed amount of liquefied carbon dioxide acquired based on the detection results of the level meter 81, thermometer 82, pressure meter 83, and purity detector 87 described above.

[0051] Furthermore, in step S13, the discharge amount acquisition unit 72 acquires the mass of carbon dioxide in the gaseous discharged from the combustion device 8 based on the fuel consumption detected by the fuel meter 88. The discharge amount acquisition unit 72 calculates the weight consumption of fuel based on the fuel consumption detected by the fuel meter 88, the fuel temperature detected by the fuel thermometer 84, and the bunker properties of the fuel loaded in the fuel tank 9 (fuel specific gravity, viscosity, calorific value, etc.). Based on the calculated fuel consumption weight, the discharge amount acquisition unit 72 calculates the amount of carbon dioxide emitted by burning the fuel during navigation using a carbon dioxide conversion factor specified by the IMO. The discharge amount acquisition unit 72 calculates the greenhouse gas reduction rate based on the difference between the amount of carbon dioxide emitted by burning the fuel during navigation and the mass of the liquefied carbon dioxide discharged from the recovery tank 22. Thereafter, the information output unit 73 outputs information based on the calculation results acquired by the discharge amount acquisition unit 72 to the outside.

[0052] Furthermore, step S14, in which liquefied carbon dioxide is fed into the recovery tank 22 after the discharge of liquefied carbon dioxide has been stopped, is carried out after the discharge of liquefied carbon dioxide from the recovery tank 22 has been stopped in step S12. This step S14 is actually carried out in parallel with step S13. In step S14, as shown in FIG. 2 , the on-off valve 27v is opened in the switching unit 27. When the on-off valve 27v is opened, the buffer tank 24 and the recovery tank 22 are connected to each other, and the transfer of liquefied carbon dioxide from the buffer tank 24 to the recovery tank 22 is resumed. Then, first, while the recovery tank 22 is discharging liquefied carbon dioxide, the liquefied carbon dioxide that has been fed into and stored in the buffer tank 24 is fed into the recovery tank 22 via the transfer piping system 103. In addition, after the on-off valve 27v is opened, while the ship 1A is at anchor, sailing, etc., newly liquefied carbon dioxide liquefied in the liquefaction section 25 is sent to the recovery tank 22 via the transfer piping system 103 and the buffer tank 24.

[0053] Step S15 of discharging liquefied carbon dioxide is performed when the recovery tank 22 discharges liquefied carbon dioxide for the second or subsequent time after the discharge of liquefied carbon dioxide from the recovery tank 22 is completed in step S12. When the ship 1A arrives at a port or the like, the recovery tank 22 discharges the liquefied carbon dioxide stored in the recovery tank 22. At this time, as shown in FIG. 3 , the switching unit 27 closes the on-off valve 27v. As a result, in step S15 of discharging liquefied carbon dioxide, only the liquefied carbon dioxide stored in the recovery tank 22 is discharged. In this case, the recovery tank 22 discharges a combination of the liquefied carbon dioxide that was sent to the buffer tank 24 and then transferred to the recovery tank 22 the previous time liquefied carbon dioxide was discharged from the recovery tank 22, and the liquefied carbon dioxide that was newly liquefied in the liquefaction unit 25 and sent to the recovery tank 22 after the discharge of liquefied carbon dioxide from the recovery tank 22 was stopped.

[0054] In step S15 of dispensing liquefied carbon dioxide, when the on-off valve 27v is closed, step S15s is executed to send liquefied carbon dioxide to the buffer tank 24. Step S15s is executed while the recovery tank 22 is dispensing liquefied carbon dioxide in step S15. In practice, step S15s is started simultaneously with closing the on-off valve 27v in step S15. In step S15s, liquefied carbon dioxide is sent to the buffer tank 24, which is the other storage section 21B from which liquefied carbon dioxide has not been dispensed, among the multiple storage sections 21 capable of storing liquefied carbon dioxide. At this time, communication between the buffer tank 24 and the recovery tank 22 via the transfer piping system 103 is cut off, and therefore, in step S15s, after the on-off valve 27v is closed, the liquefied carbon dioxide liquefied in the liquefaction section 25 is stored in the buffer tank 24.

[0055] In step S15, when the discharge of liquefied carbon dioxide from the recovery tank 22 is completed, the discharge of liquefied carbon dioxide is stopped. In step S16 of measuring the discharged liquefied carbon dioxide, the liquefied carbon dioxide discharged from the recovery tank 22 in step S15 is measured. That is, in step S16, the liquefied carbon dioxide that was sent to the buffer tank 24 while the liquefied carbon dioxide was being discharged from the recovery tank 22 and then transferred to the recovery tank 22, and the liquefied carbon dioxide that was newly liquefied in the liquefaction section 25 and sent to the recovery tank 22 after the discharge of liquefied carbon dioxide from the recovery tank 22 was stopped, are measured together. The measurement of the liquefied carbon dioxide discharged from the recovery tank 22 in step S16 may be performed in the same manner as in step S13. In this way, in step S16, the liquefied carbon dioxide that was sent to the buffer tank 24 the previous time liquefied carbon dioxide was being discharged from the recovery tank 22 and then transferred to the recovery tank 22, and the liquefied carbon dioxide that was sent to the recovery tank 22 after the discharge of liquefied carbon dioxide from the recovery tank 22 was stopped, are combined and weighed at the time of the next discharge. Here, the time of the next discharge refers to the time when liquefied carbon dioxide is again discharged from the recovery tank 22 after the discharge of liquefied carbon dioxide from the recovery tank 22 has been stopped. After this, steps S14 to S16 are repeated in sequence.

[0056] (Action and Effect) In the carbon dioxide capture system 20A of the above embodiment, when the capture tank 22, which is one of the plurality of storage units 21, is dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is sent to the buffer tank 24, which is one of the plurality of storage units 21 and is not dispensing liquefied carbon dioxide. As a result, when the capture tank 22 is dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is not sent to the capture tank 22 that is dispensing liquefied carbon dioxide. Therefore, when the liquefied carbon dioxide is being dispensed, the metering unit 80 can measure only the liquefied carbon dioxide dispensed from the capture tank 22 without being affected by the liquefied carbon dioxide liquefied in the liquefaction unit 25. As a result, the liquefied carbon dioxide dispensed from the storage unit 21 can be measured with higher accuracy.

[0057] Furthermore, in the above embodiment, at the time of the next dispensing, the liquefied carbon dioxide that is stored in the buffer tank 24 from which liquefied carbon dioxide is not being dispensed while the recovery tank 22 is dispensing liquefied carbon dioxide and the liquefied carbon dioxide that is liquefied by the liquefaction unit 25 and sent to the recovery tank 22 after the dispensing of liquefied carbon dioxide from the recovery tank 22 has stopped are dispensed. The measuring unit 80 can measure the liquefied carbon dioxide that includes the liquefied carbon dioxide that is stored in the buffer tank 24 from which liquefied carbon dioxide is not being dispensed while the recovery tank 22 is dispensing liquefied carbon dioxide.

[0058] Furthermore, in the above embodiment, when the switching unit 27 enables the transfer piping system 103 to send liquefied carbon dioxide to the recovery tank 22, the liquefied carbon dioxide liquefied by the liquefaction unit 25 is sent to the recovery tank 22 via the buffer tank 24. This allows the liquefied carbon dioxide liquefied by the liquefaction unit 25 to be collected in the recovery tank 22 when the liquefied carbon dioxide is not being dispensed. Furthermore, when the switching unit 27 blocks the transfer piping system 103 to the recovery tank 22, the liquefied carbon dioxide liquefied by the liquefaction unit 25 is sent to the buffer tank 24. This allows the liquefied carbon dioxide liquefied by the liquefaction unit 25 to be stored in the buffer tank 24 when the recovery tank 22 is dispensing liquefied carbon dioxide.

[0059] In addition, in the above embodiment, the mass of liquefied carbon dioxide dispensed from the recovery tank 22 can be obtained with high accuracy based on the liquid level levels L1, L2 of the liquefied carbon dioxide before and after being dispensed from the recovery tank 22, and the temperature and pressure at each liquid level L1, L2 in the storage section 21.

[0060] In addition, in the above embodiment, the mass of liquefied carbon dioxide discharged from the recovery tank 22 can be obtained with higher accuracy by correcting the mass of liquefied carbon dioxide discharged from the recovery tank 22 based on the purity of the liquefied carbon dioxide.

[0061] In addition, in the above embodiment, the greenhouse gas reduction rate can be calculated based on the mass of carbon dioxide gas emitted from the combustion device 8, which is obtained based on the fuel consumption detected by the fuel meter 88, and the mass of liquefied carbon dioxide discharged from the recovery tank 22.

[0062] Furthermore, the ship 1A of the above embodiment can provide a ship 1A equipped with a carbon dioxide capture system 20A that can obtain the mass of unloaded liquefied carbon dioxide with higher accuracy.

[0063] In the carbon dioxide recovery method S10 in the above embodiment, when the recovery tank 22 is discharging liquefied carbon dioxide, the liquefied carbon dioxide is sent to the buffer tank 24 from which liquefied carbon dioxide is not being discharged, so that the liquefied carbon dioxide is not sent to the recovery tank 22 from which liquefied carbon dioxide is being discharged. Therefore, when liquefied carbon dioxide is being discharged, only the liquefied carbon dioxide discharged from the recovery tank 22 can be measured without being affected by the liquefied carbon dioxide sent to the buffer tank 24. Furthermore, at the time of the next discharge, the liquefied carbon dioxide stored in the buffer tank 24 from which liquefied carbon dioxide is not being discharged while the recovery tank 22 is discharging liquefied carbon dioxide and the liquefied carbon dioxide sent to the recovery tank 22 after the discharge of liquefied carbon dioxide from the recovery tank 22 has stopped are measured together. This makes it possible to measure the liquefied carbon dioxide, including the liquefied carbon dioxide stored in the buffer tank 24 from which liquefied carbon dioxide is not being discharged while the recovery tank 22 is discharging liquefied carbon dioxide, the next time. As a result, it is possible to continuously and accurately measure the liquefied carbon dioxide dispensed from storage unit 21. Furthermore, while recovery tank 22 is dispensing liquefied carbon dioxide, the carbon dioxide liquefied in liquefaction unit 25 can be continuously stored in buffer tank 24 without affecting the measurement accuracy.

[0064] Second Embodiment Next, a second embodiment of the carbon dioxide capture system, ship, and carbon dioxide capture method according to the present disclosure will be described. In the second embodiment described below, only the configuration of the carbon dioxide capture system differs from the first embodiment, and therefore the same parts as in the first embodiment will be denoted by the same reference numerals and will not be described again. FIG. 7 is a side view of a ship according to a second embodiment of the present disclosure. FIG. 8 is a diagram showing the configuration of a carbon dioxide metering system according to the second embodiment of the present disclosure. Note that in FIG. 8, the calculation device 50 shown in FIG. 2 of the first embodiment is omitted.

[0065] (Configuration of carbon dioxide capture system) As shown in Figures 7 and 8, the carbon dioxide capture system 20B of the ship 1B illustrated in this embodiment includes a carbon dioxide capture unit 23, a liquefaction unit 25, multiple storage units 21, a switching unit 27, and a metering unit 80.

[0066] (Configuration of Storage Section) The multiple storage sections 21 exemplified in this embodiment include a first collection tank 22C and a second collection tank 22D. While the second embodiment exemplifies a case in which two storage sections 21, the first collection tank 22C and the second collection tank 22D, are provided, the number of storage sections 21 is not limited to two and may be three or more. Each of the first collection tank 22C and the second collection tank 22D is capable of storing carbon dioxide liquefied in the liquefaction section 25. The first collection tank 22C and the second collection tank 22D may be disposed on the upper deck 5 or, for example, below the upper deck 5. In this embodiment, so-called horizontally placed cylindrical tanks are exemplified as the first collection tank 22C and the second collection tank 22D, but the shapes of the first collection tank 22C and the second collection tank 22D are not limited in any way and may be, for example, spherical, rectangular, or the like.

[0067] One end of the transfer piping system 103B is connected to the liquefaction unit 25. The transfer piping system 103B branches into a first branch system 1031 and a second branch system 1032 along the way. The first branch system 1031 is connected to the first recovery tank 22C. The second branch system 1032 is connected to the second recovery tank 22D. The transfer piping system 103B sends the liquefied carbon dioxide liquefied in the liquefaction unit 25 to the first recovery tank 22C and the second recovery tank 22D.

[0068] (Configuration of switching unit) The switching unit 27 is provided in each of the first branch system 1031 and the second branch system 1032 in the transfer piping system 103B. The switching unit 27 illustrated in this embodiment is an on-off valve 27v. The on-off valve 27v provided in the first branch system 1031 can interrupt the supply of liquefied carbon dioxide to the first recovery tank 22C via the transfer piping system 103B. The on-off valve 27v provided in the second branch system 1032 can interrupt the supply of liquefied carbon dioxide to the second recovery tank 22D via the transfer piping system 103B.

[0069] 9 is a diagram showing a state in which the first recovery tank is dispensing liquefied carbon dioxide in a carbon dioxide metering system according to a second embodiment of the present disclosure. As shown in FIG. 9 , in the carbon dioxide recovery system 20B, when the first recovery tank 22C is dispensing liquefied carbon dioxide, the on-off valve 27v provided in the first branch system 1031 is closed, and the on-off valve 27v provided in the second branch system 1032 is opened. As a result, when the first recovery tank 22C is dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the second recovery tank 22D. In this case, the first recovery tank 22C serves as a storage unit 21C, one of the multiple storage units 21, and dispenses liquefied carbon dioxide. The carbon dioxide liquefied in the liquefaction unit 25 is sent to the second recovery tank 22D, which serves as another storage unit 21D, different from the storage units 21C, one of the multiple storage units 21.

[0070] 10 is a diagram showing a state in which the second recovery tank is dispensing liquefied carbon dioxide in a carbon dioxide metering system according to a second embodiment of the present disclosure. As shown in FIG. 10 , in this carbon dioxide recovery system 20B, after the first recovery tank 22C has completed dispensing liquefied carbon dioxide, the on-off valve 27v provided in the first branch system 1031 is opened and the on-off valve 27v provided in the second branch system 1032 is closed to dispense the liquefied carbon dioxide stored in the second recovery tank 22D. As a result, while the second recovery tank 22D is dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the first recovery tank 22C. In this case, the second recovery tank 22D serves as a storage unit 21C, one of the multiple storage units 21, and dispenses liquefied carbon dioxide. The carbon dioxide liquefied in the liquefaction unit 25 is sent to the first recovery tank 22C as another storage unit 21D, different from the storage units 21C, one of the multiple storage units 21.

[0071] After the second recovery tank 22D has completed the dispensing of liquefied carbon dioxide, both or either of the on-off valve 27v provided in the first branch system 1031 and the on-off valve 27v provided in the second branch system 1032 may be opened.

[0072] In this way, in the carbon dioxide capture system 20B, the liquefied carbon dioxide stored in the multiple storage sections 21 is sequentially dispensed. Then, while some storage sections 21C are dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction section 25 is sent to other storage sections 21D from which liquefied carbon dioxide is not being dispensed. As a result, the calculation device 50 (see FIG. 2) of the metering section 80 can measure the liquefied carbon dioxide sent to other storage sections 21D while some storage sections 21C are dispensing liquefied carbon dioxide after stopping the dispensing of liquefied carbon dioxide from some storage sections 21C. Furthermore, in the carbon dioxide capture system 20B exemplified in the above embodiment, while liquefied carbon dioxide is being dispensed from the second capture tank 22D, the liquefied carbon dioxide liquefied in the liquefaction section 25 is sent to the first capture tank 22C from which dispensing has already been completed. As a result, while liquefied carbon dioxide is being dispensed from storage section 21D, the liquefied carbon dioxide that has been liquefied in liquefaction section 25 and sent to first recovery tank 22C can be metered, for example, at the time of the next dispense. Here, the time of the next dispense in the second embodiment can be, for example, when the dispense of liquefied carbon dioxide stored in storage section 21 is resumed after the dispense of liquefied carbon dioxide stored in the plurality of storage sections 21 has been completed and the dispense of liquefied carbon dioxide from all storage sections 21 has stopped.

[0073] (Procedure of carbon dioxide capture method) Figure 11 is a flowchart showing the procedure of a carbon dioxide capture method according to a second embodiment of the present disclosure. As shown in Figure 11, a carbon dioxide capture method S20 according to a second embodiment of the present disclosure includes a step S21 of blocking the supply of liquefied carbon dioxide to the first capture tank, a step S22 of discharging liquefied carbon dioxide from the first capture tank, a step S22s of feeding liquefied carbon dioxide to a second capture tank, a step S23 of measuring the dispensed liquefied carbon dioxide, a step S24 of determining completion of discharging, a step S25 of blocking the supply of liquefied carbon dioxide to the second capture tank, a step S26 of discharging liquefied carbon dioxide from the second capture tank, and a step S27 of measuring the amount of liquefied carbon dioxide dispensed into the first capture tank. The method includes a step S26s of feeding carbon dioxide, a step S27 of weighing the dispensed liquefied carbon dioxide, a step S28 of determining completion of dispensing, a step S29 of blocking the feeding of liquefied carbon dioxide to the first recovery tank, a step S30 of dispensing liquefied carbon dioxide from the first recovery tank, a step S30s of feeding liquefied carbon dioxide to the second recovery tank, a step S31 of weighing the dispensed liquefied carbon dioxide, a step S32 of determining completion of dispensing, and a step S33 of stopping the dispensing of liquefied carbon dioxide and then feeding the liquefied carbon dioxide into the recovery tank.

[0074] Steps S21 to S28 described below are performed the first time liquefied carbon dioxide is dispensed from the recovery tank 22 after the start of use of the carbon dioxide capture system 20B. After the start of use of the carbon dioxide capture system 20B, for example, as shown in FIG. 8, each of the multiple on-off valves 27v is opened. Carbon dioxide contained in the exhaust gas from the combustion device 8 is recovered in the carbon dioxide capture unit 23 and then liquefied in the liquefaction unit 25. The liquefied carbon dioxide liquefied in the liquefaction unit 25 is sent to the first recovery tank 22C and the second recovery tank 22D via the transfer piping system 103B. As a result, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the first recovery tank 22C and the second recovery tank 22D.

[0075] When the ship 1B arrives at a port or the like, the liquefied carbon dioxide stored in the first collection tank 22C and the second collection tank 22D are sequentially discharged. In the second embodiment, the liquefied carbon dioxide stored in the first collection tank 22C is discharged first, followed by the liquefied carbon dioxide stored in the second collection tank 22D. However, the order of discharge is not limited to this. To achieve this, as shown in FIG. 9 , in step S21 of shutting off the supply of liquefied carbon dioxide to the first collection tank, the on-off valve 27v provided in the first branch system 1031 is closed. This blocks the supply of liquefied carbon dioxide from the liquefaction unit 25 to the first collection tank 22C. Then, the process proceeds to step S22 of discharging liquefied carbon dioxide from the first collection tank, and the discharge of the liquefied carbon dioxide stored in the first collection tank 22C begins. In this step S22, the on-off valve 27v provided in the first branch system 1031 is closed, blocking the supply of liquefied carbon dioxide from the liquefaction section 25 to the first recovery tank 22C, so that only the liquefied carbon dioxide already stored in the first recovery tank 22C is dispensed.

[0076] Step S22s of sending liquefied carbon dioxide to the second recovery tank is executed while liquefied carbon dioxide is being dispensed from first recovery tank 22C in step S22. Step S22s is actually started at the same time as closing on-off valve 27v provided in first branch system 1031 in step S21. In step S22s, after on-off valve 27v provided in first branch system 1031 is closed, the liquefied carbon dioxide liquefied in liquefaction section 25 is stored in second recovery tank 22D.

[0077] In step S23 of measuring the dispensed liquefied carbon dioxide, the liquefied carbon dioxide dispensed by the first collection tank 22C is measured. Note that the measurement of the liquefied carbon dioxide in step S23 is similar to step S13 in the first embodiment, and therefore a detailed description thereof will be omitted.

[0078] In step S24 of determining whether or not the dispensing of liquefied carbon dioxide from the first collection tank 22C is completed, it is determined whether or not the dispensing of liquefied carbon dioxide from the first collection tank 22C is completed. If the dispensing of liquefied carbon dioxide from the first collection tank 22C is not completed, steps S22, S22s, and S23 are repeated. On the other hand, if the dispensing of liquefied carbon dioxide from the first collection tank 22C is completed, the process proceeds to step S25.

[0079] In step S25 of cutting off the supply of liquefied carbon dioxide to the second recovery tank, as shown in Fig. 10 , the on-off valve 27v provided in the second branch system 1032 is closed, and the on-off valve 27v provided in the first branch system 1031 is opened. This cuts off the supply of liquefied carbon dioxide from the liquefaction unit 25 to the second recovery tank 22D.

[0080] In step S26 of discharging liquefied carbon dioxide from the second recovery tank, discharging of the liquefied carbon dioxide stored in the second recovery tank 22D begins. In this step S26, the on-off valve 27v provided in the second branch system 1032 is closed to block the feed of liquefied carbon dioxide from the liquefaction unit 25 to the second recovery tank 22D, so that only the liquefied carbon dioxide stored in the second recovery tank 22D is discharged. Here, the liquefied carbon dioxide stored in the second recovery tank 22D includes liquefied carbon dioxide that was recovered during navigation or the like and stored in the second recovery tank 22D, and liquefied carbon dioxide that was sent to the second recovery tank 22D while the above steps S22 to S23 were being performed.

[0081] Step S26s of sending liquefied carbon dioxide to the first collection tank is executed when the second collection tank 22D is dispensing liquefied carbon dioxide in step S26. Step S26s is actually started at the same time as closing the on-off valve 27v provided in the second branch system 1032 in step S25. In step S26s, after closing the on-off valve 27v provided in the second branch system 1032, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the first collection tank 22C. Note that steps S22s and S26s each correspond to the steps of sending liquefied carbon dioxide to other storage units among a plurality of storage units capable of storing liquefied carbon dioxide that are not dispensing liquefied carbon dioxide, when some storage units among a plurality of storage units capable of storing liquefied carbon dioxide are dispensing liquefied carbon dioxide, in the present disclosure.

[0082] In step S27 of measuring the dispensed liquefied carbon dioxide, the liquefied carbon dioxide dispensed from the second collection tank 22D is measured. That is, in step S22, after the dispense of liquefied carbon dioxide from the first collection tank 22C has stopped, the liquefied carbon dioxide dispensed from the second collection tank 22D is measured. The liquefied carbon dioxide measured in this step S27 includes the liquefied carbon dioxide that was sent to the second collection tank 22D while the above steps S22 to S23 were being performed. Note that the measurement of liquefied carbon dioxide in this step S27 is similar to step S13 of the first embodiment and the above-mentioned step S23, and therefore a detailed description thereof will be omitted.

[0083] In step S28 for determining completion of dispensing, it is determined whether or not the dispensing of liquefied carbon dioxide from the second collection tank 22D is completed. If the dispensing of liquefied carbon dioxide is not completed, steps S26, S26s, and S27 are repeated. On the other hand, if the dispensing of liquefied carbon dioxide from the second collection tank 22D is completed, the process proceeds to step S29.

[0084] In step S29 of cutting off the supply of liquefied carbon dioxide to the first recovery tank, the on-off valve 27v provided in the first branch system 1031 is closed. This cuts off the supply of liquefied carbon dioxide from the liquefaction unit 25 to the first recovery tank 22C.

[0085] In step S30 of discharging liquefied carbon dioxide from the first collection tank, discharging of the liquefied carbon dioxide stored in the first collection tank 22C is started. In this step S30, the on-off valve 27v provided in the first branch system 1031 is closed to block the feed of liquefied carbon dioxide from the liquefaction section 25 to the first collection tank 22C, so that only the liquefied carbon dioxide already stored in the first collection tank 22C is discharged. In this step S30, the liquefied carbon dioxide already stored in the first collection tank 22C is essentially the liquefied carbon dioxide recovered in the first collection tank 22C while the liquefied carbon dioxide was being discharged from the second collection tank 22D.

[0086] Step S30s of sending liquefied carbon dioxide to the second collection tank is performed while the first collection tank 22C is dispensing liquefied carbon dioxide in step S30. Step S30s is actually started simultaneously with closing the on-off valve 27v provided in the first branch system 1031 in step S29. In step S30s, after closing the on-off valve 27v provided in the first branch system 1031, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the second collection tank 22D. When step S30s is performed, the dispensing of the second collection tank 22D has already been completed in step 26, and therefore the liquefied carbon dioxide stored in the second collection tank 22D is essentially the liquefied carbon dioxide recovered while the liquefied carbon dioxide is being dispensed from the first collection tank 22C.

[0087] In step S31 of measuring the dispensed liquefied carbon dioxide, the liquefied carbon dioxide dispensed from the first collection tank 22C in step S30 is measured. In step S32 of determining completion of dispense, it is determined whether or not dispense of liquefied carbon dioxide from the first collection tank 22C has been completed. If dispense of liquefied carbon dioxide has not been completed, steps S30, S30s, and S31 are repeated. On the other hand, if dispense of liquefied carbon dioxide from the first collection tank 22C has been completed, the process proceeds to step S33.

[0088] In step S33 of sending liquefied carbon dioxide to the collection tank after stopping the discharge of liquefied carbon dioxide, after the discharge of liquefied carbon dioxide from the first collection tank 22C and the second collection tank 22D, i.e., all storage sections 21, has been stopped, for example, during navigation, the liquefied carbon dioxide liquefied by the liquefaction section 25 is sent to the first collection tank 22C and the second collection tank 22D, respectively, and at the time of the next discharge, the process returns to step S21 and repeats the above-mentioned series of steps. Here, the above-mentioned steps S27 and S31 each correspond to the steps of the present disclosure of stopping the discharge of liquefied carbon dioxide from some of the storage sections and then measuring the liquefied carbon dioxide stored in the other storage sections. Note that in the above second embodiment, the case where the liquefied carbon dioxide recovered in the first collection tank 22C in steps S29 to S32 is measured has been described. However, this configuration is not limited to this, and for example, steps S29 to S32 may be omitted, and the liquefied carbon dioxide sent to the first recovery tank 22C in step S26s may then be weighed together with the liquefied carbon dioxide recovered during the voyage at the time of the next dispensing.

[0089] (Action and Effect) In the carbon dioxide capture system 20B of the above embodiment, when some storage sections 21C of the multiple storage sections 21 are dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction section 25 is sent to other storage sections 21D of the multiple storage sections 21 that are not dispensing liquefied carbon dioxide. This prevents the liquefied carbon dioxide liquefied in the liquefaction section 25 from being sent to some storage sections 21C that are dispensing liquefied carbon dioxide. Therefore, when dispensing liquefied carbon dioxide, the metering section 80 can measure only the liquefied carbon dioxide dispensed from some storage sections 21C without being affected by the liquefied carbon dioxide liquefied in the liquefaction section 25. As a result, similar to the first embodiment, the liquefied carbon dioxide dispensed from the storage section 21 can be measured with higher accuracy.

[0090] (Variation of Second Embodiment) In the second embodiment described above, the first collection tank 22C and the second collection tank 22D are provided as the multiple storage sections 21, but this is not limited to this. Fig. 13 is a diagram showing the configuration of a carbon dioxide metering system according to a variation of the second embodiment of the present disclosure. In Fig. 13, the metering section 80 is not shown. As shown in Fig. 13, in a carbon dioxide capture system 20C of this variation, the multiple storage sections 21 are formed by dividing a single tank 28 into multiple sections.

[0091] The tank 28 is capable of storing the carbon dioxide liquefied by the liquefaction unit 25. The tank 28 may be located on the upper deck 5 or, for example, below the upper deck 5. In this embodiment, a so-called horizontally placed cylindrical tank is exemplified as the tank 28, but the shape of the tank 28 is not limited in any way and may be, for example, spherical or rectangular.

[0092] The tank 28 includes a partition 28k that divides the interior of the tank 28 into multiple sections (for example, two). By dividing the interior of the tank 28 into multiple sections by the partition 28k, a first storage compartment 26E and a second storage compartment 26F are formed within the tank 28. While the tank 28 illustrated in this embodiment has the first storage compartment 26E and the second storage compartment 26F formed therein, the number of storage compartments formed within the tank 28 is not limited to two, and may be three or more. Each of the first storage compartment 26E and the second storage compartment 26F is capable of storing carbon dioxide liquefied in the liquefaction unit 25.

[0093] One end of the transfer piping system 103C is connected to the liquefaction unit 25. The transfer piping system 103C branches into a first branch system 1033 and a second branch system 1034 along the way. The first branch system 1033 is connected to the first storage compartment 26E. The second branch system 1034 is connected to the second storage compartment 26F. The transfer piping system 103C sends the liquefied carbon dioxide liquefied in the liquefaction unit 25 to the first storage compartment 26E and the second storage compartment 26F.

[0094] (Configuration of switching unit) The switching unit 27 is provided in each of the first branch system 1033 and the second branch system 1034 in the transfer piping system 103C. The switching unit 27 illustrated in this embodiment is an on-off valve 27v. The on-off valve 27v provided in the first branch system 1033 can interrupt the supply of liquefied carbon dioxide to the first storage compartment 26E via the transfer piping system 103C. The on-off valve 27v provided in the second branch system 1034 can interrupt the supply of liquefied carbon dioxide to the second storage compartment 26F via the transfer piping system 103C.

[0095] 14 is a diagram showing a state in which the first storage compartment is dispensing liquefied carbon dioxide in a carbon dioxide metering system according to a modified example of the second embodiment of the present disclosure. As shown in FIG. 14, when the first storage compartment 26E is dispensing liquefied carbon dioxide, the switching unit 27 closes the on-off valve 27v provided in the first branch system 1033 and opens the on-off valve 27v provided in the second branch system 1034. As a result, when the first storage compartment 26E is dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the second storage compartment 26F. In this case, the first storage compartment 26E dispenses liquefied carbon dioxide as a storage section 21C, which is one of the multiple storage sections 21. The liquefied carbon dioxide liquefied in the liquefaction unit 25 is sent to the second storage compartment 26F as another storage section 21D, which is one of the multiple storage sections 21.

[0096] 15 is a diagram showing a state in which the second storage compartment is dispensing liquefied carbon dioxide in a carbon dioxide metering system according to a modified example of the second embodiment of the present disclosure. As shown in FIG. 15, when the second storage compartment 26F is dispensing liquefied carbon dioxide, the switching unit 27 closes the on-off valve 27v provided in the second branch system 1034 and opens the on-off valve 27v provided in the first branch system 1033. As a result, when the second storage compartment 26F is dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction unit 25 is stored in the first storage compartment 26E. In this case, the second storage compartment 26F dispenses liquefied carbon dioxide as a storage section 21C, which is one of the multiple storage sections 21. The liquefied carbon dioxide liquefied in the liquefaction unit 25 is sent to the first storage compartment 26E as another storage section 21D, which is one of the multiple storage sections 21.

[0097] In this way, in the carbon dioxide capture system 20C, liquefied carbon dioxide stored in the multiple storage sections 21 is sequentially dispensed, as in the second embodiment described above. Then, while some storage sections 21C are dispensing liquefied carbon dioxide, liquefied carbon dioxide liquefied in the liquefaction section 25 is sent to other storage sections 21D that are not dispensing liquefied carbon dioxide. In other words, liquefied carbon dioxide is not sent to some storage sections 21C that are dispensing liquefied carbon dioxide. Therefore, while some storage sections 21C are dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction section 25 can be measured with high accuracy. Furthermore, in the carbon dioxide capture system 20C, while liquefied carbon dioxide is being dispensed from the second storage section 26F, liquefied carbon dioxide liquefied in the liquefaction section 25 is sent to the first storage section 26E that has already completed dispensing. This allows the liquefied carbon dioxide that is liquefied in the liquefaction section 25 and sent to the first storage section 26E while liquefied carbon dioxide is being dispensed from the second storage section 26F to be weighed, for example, at the time of the next dispense.

[0098] In carbon dioxide capture system 20C of this modified example, a plurality of storage sections 21 formed in tank 28 is used, and while one storage section 21C of the plurality of storage sections 21 is dispensing liquefied carbon dioxide, liquefied carbon dioxide liquefied in liquefaction section 25 can be sent to another storage section 21D. Furthermore, in the above modified example, as in the second embodiment, the liquefied carbon dioxide dispensed from storage section 21 can be measured with higher accuracy.

[0099] (Other Embodiments) Although the embodiments of the present disclosure have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design modifications and the like are also included within the scope of the gist of the present disclosure. For example, in the above embodiment, the flow meter 92 detects the flow rate of liquefied carbon dioxide dispensed by the dispensing piping system 104, but the flow meter 92 may also detect the pressure and temperature of the liquefied carbon dioxide flowing through the dispensing piping system 104. In this way, the mass flow rate of liquefied carbon dioxide dispensed by the dispensing piping system 104 can be obtained based on the volumetric flow rate of liquefied carbon dioxide detected by the flow meter 92 and the pressure and temperature of the liquefied carbon dioxide flowing through the dispensing piping system 104.

[0100] In addition, while using a flow meter 92 that detects the volumetric flow rate of liquefied carbon dioxide, the mass flow rate of liquefied carbon dioxide flowing through the dispensing piping system 104 can be obtained based on the pressure of the liquefied carbon dioxide detected by the pressure meter 83 and the temperature of the liquefied carbon dioxide detected by the thermometer 82.

[0101] Furthermore, the flow meter 92 may be configured to detect the mass flow rate of the liquefied carbon dioxide flowing through the dispensing piping system 104. This allows for more accurate abnormality detection by comparing the detection result of the flow meter 92 with the mass of the liquefied carbon dioxide dispensed from the storage unit 21.

[0102] Furthermore, in the above embodiment, the purity of the liquefied carbon dioxide is detected by the purity detector 87, but the detection position of the purity of the liquefied carbon dioxide may be, for example, inside the storage section 21. Furthermore, in the above embodiment, the mass of the liquefied carbon dioxide dispensed from the recovery tank 22 is corrected based on the purity of the liquefied carbon dioxide detected by the purity detector 87, but the correction based on the purity of the liquefied carbon dioxide may be omitted depending on the purpose of use of the liquefied carbon dioxide, etc.

[0103] <Additional Notes> The carbon dioxide capture systems 20A, 20B, and 20C, ships 1A and 1B, and carbon dioxide capture methods S10 and S20 described in the respective embodiments can be understood, for example, as follows.

[0104] (1) The carbon dioxide capture systems 20A, 20B, and 20C according to the first aspect include a carbon dioxide capture unit 23 that captures gaseous carbon dioxide from a carbon dioxide-containing gas, a liquefaction unit 25 that liquefies the gaseous carbon dioxide captured by the carbon dioxide capture unit 23, a plurality of storage units 21 capable of storing the liquefied carbon dioxide liquefied by the liquefaction unit 25, a switching unit 27 that sends the liquefied carbon dioxide liquefied in the liquefaction unit 25 to the other storage units 21B and 21D of the plurality of storage units 21 that are not discharging liquefied carbon dioxide when some of the storage units 21A and 21C of the plurality of storage units 21 are discharging liquefied carbon dioxide, and a measuring unit 80 that measures the liquefied carbon dioxide dispensed from the storage unit 21.

[0105] This prevents liquefied carbon dioxide liquefied in liquefaction unit 25 from being sent to some of the storage units 21A, 21C that are dispensing liquefied carbon dioxide. Therefore, when liquefied carbon dioxide is being dispensed, metering unit 80 can measure only the liquefied carbon dioxide dispensed from some of the storage units 21A, 21C without being affected by the liquefied carbon dioxide liquefied in liquefaction unit 25. As a result, the liquefied carbon dioxide dispensed from storage unit 21 is measured with higher accuracy. Furthermore, when some of the storage units 21A, 21C are dispensing liquefied carbon dioxide, the carbon dioxide liquefied in liquefaction unit 25 can be continuously stored in the other storage units 21B, 21D without affecting the metering accuracy.

[0106] (2) The carbon dioxide capture systems 20A, 20B, and 20C according to the second aspect are the carbon dioxide capture systems 20A, 20B, and 20C of (1), in which, while some of the storage sections 21C are dispensing liquefied carbon dioxide, the liquefied carbon dioxide stored in other storage sections 21D that are not dispensing liquefied carbon dioxide is weighed after stopping the dispensing of liquefied carbon dioxide from some of the storage sections 21C.

[0107] This makes it possible to measure liquefied carbon dioxide including liquefied carbon dioxide sent to other storage sections 21B, 21D that are not dispensing liquefied carbon dioxide while some storage sections 21A, 21C are dispensing liquefied carbon dioxide. Also, while some storage sections 21B, 21C are dispensing liquefied carbon dioxide, carbon dioxide liquefied in liquefaction section 25 can be continuously stored without affecting the measurement accuracy.

[0108] (3) The carbon dioxide capture systems 20A, 20B, and 20C according to the third aspect are the carbon dioxide capture systems 20A, 20B, and 20C of (1) or (2), in which the measuring unit 80 measures the liquefied carbon dioxide stored in the other storage units 21B and 21D that are not dispensing liquefied carbon dioxide while some of the storage units 21A and 21C are dispensing liquefied carbon dioxide, together with the liquefied carbon dioxide that has been liquefied by the liquefaction unit 25 and sent to one of the plurality of storage units 21 after the dispensing of liquefied carbon dioxide from some of the storage units 21A and 21C has stopped, at the time of the next dispensing.

[0109] This makes it possible to measure liquefied carbon dioxide including liquefied carbon dioxide stored in other storage sections 21B that are not dispensing liquefied carbon dioxide when some storage sections 21A, 21C are dispensing liquefied carbon dioxide. Also, when some storage sections 21A, 21C are dispensing liquefied carbon dioxide, carbon dioxide liquefied in liquefaction section 25 can be stored continuously without affecting the measurement accuracy.

[0110] (4) The carbon dioxide recovery system 20A, 20B, 20C relating to the fourth aspect is any one of the carbon dioxide recovery systems 20A, 20B, 20C of (1) to (3), in which the other storage section 21B is a buffer tank 24, and some of the storage sections 21A, 21C are recovery tanks 22 to which liquefied carbon dioxide liquefied by the liquefaction section 25 is sent when liquefied carbon dioxide is not being dispensed, the buffer tank 24 is provided midway through a transfer piping system 103 that sends liquefied carbon dioxide from the liquefaction section 25 to the recovery tank 22, and the switching section 27 is capable of interrupting the sending of liquefied carbon dioxide to the recovery tank 22 by the transfer piping system 103.

[0111] As a result, when liquefied carbon dioxide is not being discharged, the liquefied carbon dioxide liquefied by the liquefaction unit 25 can be recovered in the recovery tank 22. Furthermore, when the recovery tank 22 is discharging liquefied carbon dioxide, the liquefied carbon dioxide liquefied by the liquefaction unit 25 can be sent to the buffer tank 24.

[0112] (5) The carbon dioxide capture system 20C according to the fifth aspect is any one of the carbon dioxide capture systems 20C described in (1) to (3), and the plurality of storage sections 21 are formed by dividing the inside of a hollow tank 28 into a plurality of sections.

[0113] This allows the use of multiple storage sections 21 formed within the tank 28, and while one of the multiple storage sections 21, storage section 21C, is dispensing liquefied carbon dioxide, the liquefied carbon dioxide liquefied in the liquefaction section 25 can be sent to another storage section 21D.

[0114] (6) The carbon dioxide capture system 20A, 20B, 20C relating to the sixth aspect is any one of the carbon dioxide capture systems 20A, 20B, 20C of (1) to (5), wherein the measuring unit 80 includes a level meter 81 that detects the liquid level in the storage unit 21, a thermometer 82 that detects the temperature in the storage unit 21, and a pressure meter 83 that detects the pressure in the storage unit 21, and the measuring unit 80 obtains the mass of liquefied carbon dioxide stored in the storage unit 21 based on the detection results of the level meter 81, the thermometer 82, and the pressure meter 83.

[0115] This makes it possible to obtain with high accuracy the mass of liquefied carbon dioxide dispensed from the storage section 21 based on the volume of liquefied carbon dioxide dispensed from the storage section 21 and the temperature and pressure within the storage section 21.

[0116] (7) The carbon dioxide capture systems 20A, 20B, and 20C relating to the seventh aspect are the carbon dioxide capture systems 20A, 20B, and 20C of (6), and further include a purity detector 87 that detects the purity of the liquefied carbon dioxide dispensed from the storage section 21, and the measuring section 80 corrects the mass of the liquefied carbon dioxide dispensed from the storage section 21 based on the purity of the liquefied carbon dioxide detected by the purity detector 87.

[0117] This allows the mass of liquefied carbon dioxide dispensed from the storage section 21 to be corrected based on the purity of the liquefied carbon dioxide, thereby making it possible to obtain the mass of liquefied carbon dioxide dispensed from the storage section 21 with greater accuracy.

[0118] (8) The carbon dioxide capture system 20A, 20B, 20C relating to the eighth aspect is any one of the carbon dioxide capture systems 20A, 20B, 20C of (1) to (7), and further comprises a combustion device 8 that burns fuel and a fuel meter 88 that can detect the amount of fuel consumed by the combustion device 8, and the measurement unit 80 acquires the amount of carbon dioxide emitted from the combustion device 8 based on the amount of fuel consumed detected by the fuel meter 88, and calculates the greenhouse gas reduction rate based on the acquisition result of the amount of carbon dioxide emitted from the combustion device 8 and the measurement result of the liquefied carbon dioxide dispensed from the storage unit 21.

[0119] This makes it possible to calculate the greenhouse gas reduction rate based on the mass of carbon dioxide in the gas emitted from the combustion device 8, which is obtained based on the amount of fuel consumed detected by the fuel meter 88, and the amount of liquefied carbon dioxide dispensed from the storage section 21.

[0120] (9) The ships 1A and 1B according to the ninth aspect include a hull 2 ​​and any one of the carbon dioxide capture systems 20A, 20B, and 20C according to (1) to (8).

[0121] This makes it possible to provide ships 1A, 1B equipped with carbon dioxide capture systems 20A, 20B, 20C that can measure the liquefied carbon dioxide discharged from the storage section 21 with higher accuracy.

[0122] (10) The carbon dioxide recovery method according to the tenth aspect includes steps S12s, S15s, S22s, S26s, and 30s of pumping liquefied carbon dioxide into other storage sections 21B and 21D of a plurality of storage sections 21 capable of storing liquefied carbon dioxide when some of the storage sections 21A and 21C of the plurality of storage sections 21 capable of storing liquefied carbon dioxide are discharging liquefied carbon dioxide, and steps S16, S27, and S31 of weighing the liquefied carbon dioxide pumped into the other storage sections 21B and 21D while liquefied carbon dioxide is being discharged from some of the storage sections 21A and 21C after stopping the discharge of liquefied carbon dioxide from some of the storage sections 21A and 21C. As a result, when liquefied carbon dioxide is being dispensed from some of the storage sections 21A, 21C, only the liquefied carbon dioxide dispensed from some of the storage sections 21A, 21C can be measured without being affected by liquefied carbon dioxide being sent to the other storage sections 21B, 21D. Furthermore, when liquefied carbon dioxide is being dispensed from some of the storage sections 21A, 21C, the liquefied carbon dioxide stored in the other storage sections 21B, 21D can also be measured individually after the dispensing of liquefied carbon dioxide from some of the storage sections 21A, 21C has stopped. As a result, the liquefied carbon dioxide dispensed from some of the storage sections 21A, 21C and the liquefied carbon dioxide stored in the other storage sections 21B, 21D can be measured with higher accuracy.

[0123] (11) The carbon dioxide recovery method according to the eleventh aspect is the carbon dioxide recovery method of (10), wherein in step S16, the liquefied carbon dioxide that was sent to some of the storage sections 21B while liquefied carbon dioxide was being dispensed from other storage sections 21A is weighed after the dispense of liquefied carbon dioxide from some of the storage sections 21A is stopped, the liquefied carbon dioxide that was sent to other storage sections 21B while liquefied carbon dioxide was being dispensed from some of the storage sections 21A and the liquefied carbon dioxide that was sent to any of the multiple storage sections 21 after the dispense of liquefied carbon dioxide from some of the storage sections 21A is stopped are combined and weighed at the time of the next dispense.

[0124] This allows only the liquefied carbon dioxide dispensed from some of the storage sections 21A to be metered without being affected by the liquefied carbon dioxide sent to other storage sections 21B when liquefied carbon dioxide is being dispensed. Furthermore, at the time of the next dispense, it is possible to measure together the liquefied carbon dioxide stored in other storage sections 21B from which liquefied carbon dioxide is not being dispensed while some of the storage sections 21A are dispensing liquefied carbon dioxide, and the liquefied carbon dioxide sent to any of the multiple storage sections 21 after the dispensing of liquefied carbon dioxide from some of the storage sections 21A has stopped. As a result, the liquefied carbon dioxide dispensed from the storage sections 21 can be measured with higher accuracy. Furthermore, when some of the storage sections 21A are dispensing liquefied carbon dioxide, the carbon dioxide liquefied in the liquefaction section 25 can be continuously stored without affecting the metering accuracy.

[0125] According to the carbon dioxide capture system, ship, and carbon dioxide capture method disclosed herein, the liquefied carbon dioxide discharged from the storage section can be measured with greater accuracy.

[0126] DESCRIPTION OF SYMBOLS 1A, 1B Ship 2 Hull 2a Bow 2b Stern 3A, 3B Side 4 Ship bottom 5 Upper deck 6 Superstructure 7 Cargo loading compartment 8 Combustion device 9 Fuel tank 11 Cargo tank 20A-20C Carbon dioxide capture system 21, 21A-21D Storage section 22 Capture tank 22C First capture tank 22D Second capture tank 23 Carbon dioxide capture section 24 Buffer tank 25 Liquefaction section 26E First storage section 26F Second storage section 27 Switching section 27v Opening / closing valve 28 Tank 28k Partition 50 Arithmetic unit 51 CPU 52 ROM 53 RAM 54 Storage 55 Signal transmission / reception module 70 Signal input section 71 Information acquisition section 72 Discharge amount acquisition section 73 Information output unit 80 Measuring unit 81 Level gauge 82 Thermometer 83 Pressure gauge 84 Fuel temperature gauge 87 Purity detector 88 Fuel gauge 92 Flow meter 101 Fuel supply piping system 102 Exhaust gas pipe 103, 103B, 103C Transfer piping system 104 Discharge piping system 105 Discharge piping system 108 Lifting pump 1031, 1033 First branch system 1032, 1034 Second branch system L1, L2 Liquid level

Claims

1. A carbon dioxide capture system comprising: a carbon dioxide capture unit that captures gaseous carbon dioxide from a carbon dioxide-containing gas; a liquefaction unit that liquefies the gaseous carbon dioxide captured by the carbon dioxide capture unit; a plurality of storage units capable of storing the liquefied carbon dioxide liquefied by the liquefaction unit; a switching unit that, when some of the plurality of storage units are dispensing liquefied carbon dioxide, sends the liquefied carbon dioxide liquefied in the liquefaction unit to other of the plurality of storage units that are not dispensing liquefied carbon dioxide; and a measuring unit that measures the liquefied carbon dioxide dispensed from the storage unit.

2. A carbon dioxide capture system as described in claim 1, wherein while some of the storage sections are discharging liquefied carbon dioxide, the liquefied carbon dioxide stored in other storage sections that are not discharging liquefied carbon dioxide is weighed after the discharging of liquefied carbon dioxide from some of the storage sections is stopped.

3. A carbon dioxide capture system as described in claim 1 or 2, wherein the measuring unit measures the liquefied carbon dioxide stored in other storage units that are not dispensing liquefied carbon dioxide while some of the storage units are dispensing liquefied carbon dioxide, and the liquefied carbon dioxide that has been liquefied by the liquefaction unit and sent to any one of the plurality of storage units after the dispensing of liquefied carbon dioxide from some of the storage units has been stopped, at the time of the next dispensing.

4. A carbon dioxide capture system as described in claim 1 or 2, wherein other of the storage sections are buffer tanks, and some of the storage sections are recovery tanks to which liquefied carbon dioxide liquefied by the liquefaction section is sent when liquefied carbon dioxide is not being discharged, the buffer tank is provided midway through a transfer piping system that sends liquefied carbon dioxide from the liquefaction section to the recovery tank, and the switching section is capable of interrupting the sending of liquefied carbon dioxide to the recovery tank via the transfer piping system.

5. A carbon dioxide capture system as described in claim 1 or 2, wherein the multiple storage sections are formed by dividing a hollow tank into multiple sections.

6. A carbon dioxide capture system as described in claim 1 or 2, wherein the measuring unit is provided with a level gauge that detects the liquid level in the storage unit, a thermometer that detects the temperature in the storage unit, and a pressure gauge that detects the pressure in the storage unit, and the measuring unit obtains the mass of liquefied carbon dioxide stored in the storage unit based on the detection results of the level gauge, the thermometer, and the pressure gauge.

7. The carbon dioxide capture system described in claim 6, further comprising a purity detector that detects the purity of the liquefied carbon dioxide dispensed from the storage section, and the measuring section corrects the mass of the liquefied carbon dioxide dispensed from the storage section based on the purity of the liquefied carbon dioxide detected by the purity detector.

8. A carbon dioxide capture system as described in claim 1 or 2, further comprising: a combustion device that burns fuel; and a fuel meter capable of detecting the amount of fuel consumed by the combustion device, wherein the measurement unit obtains the amount of carbon dioxide emitted from the combustion device based on the amount of fuel consumed detected by the fuel meter, and calculates a greenhouse gas reduction rate based on the obtained amount of carbon dioxide emitted from the combustion device and the measurement result of the liquefied carbon dioxide dispensed from the storage unit.

9. A ship comprising a hull and a carbon dioxide capture system according to claim 1 or 2.

10. A carbon dioxide recovery method comprising the steps of: sending liquefied carbon dioxide to other storage sections among a plurality of storage sections capable of storing liquefied carbon dioxide that are not discharging liquefied carbon dioxide when one of the storage sections is discharging liquefied carbon dioxide; sending liquefied carbon dioxide to any one of the plurality of storage sections after stopping the discharging of liquefied carbon dioxide from some of the storage sections; and weighing the liquefied carbon dioxide sent to the other storage sections while liquefied carbon dioxide is being discharged from some of the storage sections after stopping the discharging of liquefied carbon dioxide from some of the storage sections.

11. A carbon dioxide recovery method as described in claim 10, wherein in the process of weighing the liquefied carbon dioxide that was sent to some of the storage sections while liquefied carbon dioxide was being discharged from other of the storage sections after the discharge of liquefied carbon dioxide from some of the storage sections is stopped, the liquefied carbon dioxide that was sent to the other of the storage sections while liquefied carbon dioxide was being discharged from some of the storage sections and the liquefied carbon dioxide that was sent to any of the plurality of storage sections after the discharge of liquefied carbon dioxide from some of the storage sections is stopped are combined and weighed at the time of the next discharge.

Images