Inert gas supply system, vessel, and inert gas supply method

Abstract

To provide an inert gas supply system capable of suppressing energy consumption and of suppressing greenhouse effect gas emission.SOLUTION: An inert gas supply system is provided in a ship and is the one capable of supplying an inert gas to a tank which can store a crude oil or petroleum refining products. The inert gas supply system comprises a carbon dioxide recovery part to recover the carbon dioxide included in an exhaust gas from a combustion apparatus for burning a fuel, and an inert gas supply part to supply the carbon dioxide recovered by the carbon dioxide recovery part to the tank as an inert gas.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an inert gas supply system, a ship, and an inert gas supply method.

Background Art

[0002] In a ship that transports a volatile liquid such as crude oil or petroleum refined products, the volatile liquid may be stored in a tank together with inert gas (inert gas). Patent Document 1 discloses an inert gas supply system that supplies inert gas obtained by purifying exhaust gas from an engine or boiler for ship propulsion into a tank (cargo tank) of a ship. This inert gas supply system includes an exhaust gas introduction passage, an exhaust gas purification device, and an inert gas supply passage. The exhaust gas introduction passage is connected to an exhaust pipe of an engine or boiler for ship propulsion. The exhaust gas purification device purifies the exhaust gas. The inert gas supply passage supplies the inert gas generated by the exhaust gas purification device into the tank.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration described in Patent Document 1, depending on the ship's operating conditions, the engine or boiler may need to be driven solely to supply inert gas to the tank. Furthermore, a fan installed in the inert gas supply path needs to be driven to supply inert gas to the tank. Driving such engines, boilers, and fans requires energy such as fuel. Moreover, a common challenge in international shipping is the reduction of greenhouse gases (GHG), including carbon dioxide (CO2), and the effective utilization and storage of carbon dioxide. Therefore, in ships, reducing carbon dioxide emissions by minimizing energy consumption through inert gas supply systems is desirable.

[0005] This disclosure was made to solve the above-mentioned problems and aims to provide an inert gas supply system, a vessel, and an inert gas supply method that can reduce greenhouse gas emissions. [Means for solving the problem]

[0006] To solve the above problems, the inert gas supply system according to this disclosure is an inert gas supply system installed on a ship that can supply inert gas to a tank capable of storing crude oil or petroleum refined products. The inert gas supply system comprises a carbon dioxide recovery unit and an inert gas supply unit, Carbon dioxide storage section, The system includes the following: The carbon dioxide recovery unit recovers carbon dioxide contained in the exhaust gas from the combustion device that burns the fuel. The inert gas supply unit supplies the carbon dioxide recovered by the carbon dioxide recovery unit to the tank as inert gas. The carbon dioxide storage unit stores the carbon dioxide recovered in the carbon dioxide recovery unit. The inert gas supply unit supplies the carbon dioxide stored in the carbon dioxide storage unit to the gas phase in the tank as the level of the liquid phase in the tank decreases when the crude oil or petroleum refined product is being discharged from the tank to the outside of the tank. Furthermore, the inert gas supply system according to this disclosure is an inert gas supply system installed on a ship and capable of supplying inert gas to a tank capable of storing crude oil or petroleum refined products, comprising: a carbon dioxide recovery unit that recovers carbon dioxide contained in exhaust gas from a combustion device that burns fuel; and an inert gas supply unit that supplies the carbon dioxide recovered by the carbon dioxide recovery unit to the tank as inert gas, wherein the carbon dioxide is supplied into the tank when the pressure inside the tank falls below the pressure outside the tank due to fluctuations in outside temperature.

[0007] The vessel relating to this disclosure comprises a hull, a tank, and the inert gas supply system described above. The tank is provided in the hull. The tank is capable of storing crude oil or petroleum refined products.

[0008] The inert gas supply method relating to this disclosure is an inert gas supply method in the above-described inert gas supply system. The inert gas supply method includes a step of recovering carbon dioxide and a step of supplying carbon dioxide to a tank. The step of recovering carbon dioxide recovers carbon dioxide contained in the exhaust gas from a combustion device that burns fuel. The step of supplying carbon dioxide to a tank supplies the recovered carbon dioxide to the tank as inert gas. [Effects of the Invention]

[0009] According to the inert gas supply system, vessel, and inert gas supply method of this disclosure, greenhouse gas emissions can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1] This is a side view of a floating body equipped with an inert gas supply system, a vessel, and an inert gas supply method according to an embodiment of the present disclosure. [Figure 2] This figure shows the configuration of an inert gas supply system according to the first embodiment of this disclosure. [Figure 3] This is a flowchart showing the procedure for an inert gas supply method according to each embodiment of the present disclosure. [Figure 4] This figure shows the inert gas supply status during navigation of a vessel according to the first embodiment of this disclosure. [Figure 5] This figure shows the supply state of inert gas during unloading of a vessel according to the first embodiment of this disclosure. [Figure 6] This figure shows the inert gas supply status during unloaded navigation of a vessel according to the first embodiment of this disclosure. [Figure 7] This figure shows the discharge state of inert gas during loading of a vessel according to the first embodiment of this disclosure. [Figure 8] This figure shows the configuration of the inert gas supply system according to the second embodiment of this disclosure. [Figure 9]This is a diagram showing the supply state of inert gas during the navigation of a ship according to the second embodiment of the present disclosure. [Figure 10] This is a diagram showing the supply state of inert gas during the loading of a ship according to the second embodiment of the present disclosure. [Figure 11] This is a diagram showing the supply state of inert gas during the light-load navigation of a ship according to the second embodiment of the present disclosure. [Figure 12] This is a diagram showing the payout state of inert gas during the loading of a ship according to the second embodiment of the present disclosure. [Figure 13] This is a diagram showing the payout state of inert gas in a ship according to the second embodiment of the present disclosure. [Figure 14] This is a diagram showing the configuration of an inert gas supply system according to the third embodiment of the present disclosure. [Figure 15] This is a diagram showing the supply state of inert gas during the navigation of a ship according to the third embodiment of the present disclosure. [Figure 16] This is a diagram showing the supply state of inert gas during the loading of a ship according to the third embodiment of the present disclosure. [Figure 17] This is a diagram showing the supply state of inert gas during the light-load navigation of a ship according to the third embodiment of the present disclosure. [Figure 18] This is a diagram showing the payout state of inert gas during the loading of a ship according to the third embodiment of the present disclosure. [Figure 19] This is another diagram showing the payout state of inert gas in a ship according to the third embodiment of the present disclosure.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, an inert gas supply system, a ship, and an inert gas supply method according to embodiments of the present disclosure will be described with reference to FIGS. 1 to 19. <First Embodiment> (Overall Configuration of the Ship) As shown in Figure 1, the vessel 1 of this embodiment of the disclosure comprises at least a hull 2, a superstructure 4, a combustion device 9, a tank 10, and an inert gas supply system 20A. The vessel 1 of this embodiment is described as a vessel capable of navigation by a main engine, etc., as an example. The type of vessel 1 is not limited to a specific type. Examples of vessel types for vessel 1 include liquid carriers such as tankers that transport crude oil or liquid petroleum refined products refined from crude oil. Examples of petroleum refined products include gasoline, kerosene, naphtha, methanol, etc.

[0012] The hull 2 ​​has a pair of side panels 5A and 5B that form its outer shell, and a bottom 6. The side panels 5A and 5B are each provided with a pair of side plates that form the port and starboard sides, respectively. The bottom 6 is provided with bottom plates that connect these side panels 5A and 5B.

[0013] The hull 2 ​​further includes an upper deck 7, which is a full-length deck located at the very top. The superstructure 4 is formed on this upper deck 7. Living quarters and other facilities are located within the superstructure 4. In this embodiment of the vessel 1, for example, a cargo hold 8 is formed on the bow 2a side in the forward-stern direction FA from the superstructure 4. A tank 10 is housed within the cargo hold 8 in this embodiment.

[0014] The combustion device 9 is a device that generates thermal energy by burning fuel and is installed inside the hull 2 ​​described above. Examples of combustion devices 9 include an internal combustion engine used as the main engine for propelling the ship 1, 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.

[0015] (Configuration of the tank equipment) Multiple tanks 10 are arranged in a row in the cargo loading compartment 8. In this embodiment, an example is shown where five tanks 10A to 10E are arranged at intervals in the bow-stern direction FA. Each tank 10 contains a liquid L, such as crude oil or refined petroleum products that are liquid at room temperature and are refined from crude oil. The number and arrangement of tanks 10 in the cargo loading compartment 8 are not limited to the above number and arrangement. Also, the shape of the tanks 10 is not limited to the shape shown in Figure 1, etc.

[0016] (Configuration of the inert gas supply system) Figure 2 shows the configuration of an inert gas supply system according to the first embodiment of this disclosure. As shown in Figure 2, the vessel 1 is equipped with a liquid piping section 15 for loading and unloading liquid L into and from each of the multiple tanks 10. The liquid piping section 15 includes a connecting pipe 16 and multiple branch pipes 17.

[0017] The connecting pipe 16 is connected to a bunker station (not shown) or the like, and can be connected to external facilities such as storage facilities 200 (see Figure 5) and supply facilities 300 (see Figure 7) outside the ship 1 via this bunker station. An on-off valve 16v is provided in the middle of the connecting pipe 16 to intermittently supply liquid L through the connecting pipe 16. In this embodiment, an example is given in which only one on-off valve 16v is provided on the side closer to the bunker station (not shown) than the branch pipe 17, but the number and arrangement of on-off valves 16v are not limited to the above configuration, as long as they can intermittently supply liquid L through the connecting pipe 16.

[0018] Multiple branch pipes 17 are provided to connect the inside of each tank 10 with the connecting pipe 16. Each of the multiple branch pipes 17 is equipped with a valve to intermittently interrupt the flow of liquid L through the branch pipe 17, and a loading pump or the like (neither shown) for supplying liquid L to the outside of the tank 10 through the branch pipe 17. Note that the liquid piping section 15 is not limited to the above configuration. For example, a loading liquid piping section 15 for loading liquid L into each of the multiple tanks 10 and a loading liquid piping section 15 for unloading liquid L may be provided separately.

[0019] (Configuration of the inert gas supply system) The inert gas supply system 20A is capable of supplying inert gas G to the tank 10. The inert gas supply system 20A includes a carbon dioxide recovery unit 21, an inert gas supply unit 22A, and a carbon dioxide discharge unit 50.

[0020] The carbon dioxide recovery unit 21 recovers carbon dioxide from the exhaust gas of the combustion device 9. The inert gas supply system 20A exemplified in this embodiment is installed on the upper deck 7 of the hull 2, but the placement of the inert gas supply system 20A is not limited to the upper deck 7.

[0021] Here, as a method for recovering carbon dioxide contained in exhaust gas by the carbon dioxide recovery unit 21, a method can be used in which the carbon dioxide contained in the exhaust gas is absorbed into an absorbent liquid by a chemical absorption method and then recovered. An example of an absorbent liquid for which carbon dioxide is absorbed by a chemical absorption method is MEA (monoethanolamine). When MEA is heated, the absorbed carbon dioxide is separated into a gaseous state, and the carbon dioxide recovery unit 21 recovers this separated carbon dioxide. Although the above description has been given for the case in which the carbon dioxide recovery unit 21 recovers carbon dioxide using a chemical absorption method with MEA, the configuration is not limited to the above as long as it is possible to recover carbon dioxide contained in exhaust gas.

[0022] The inert gas supply unit 22A supplies carbon dioxide recovered by the carbon dioxide recovery unit 21 to the tank 10 as inert gas G. In the first embodiment of this disclosure, the inert gas supply unit 22A includes a carbon dioxide supply pipe 23A and a piping section 24A.

[0023] One end of the carbon dioxide supply pipe 23A is connected to the carbon dioxide recovery unit 21. The other end of the carbon dioxide supply pipe 23A is connected to the piping unit 24A. An on-off valve 231 is provided in the middle of the carbon dioxide supply pipe 23A. The on-off valve 231 intermittently supplies carbon dioxide from the carbon dioxide recovery unit 21 through the carbon dioxide supply pipe 23A.

[0024] The piping section 24A includes a connecting pipe 26A and a plurality of branch pipes 27. The connecting pipe 26A is connected to the other end of the carbon dioxide supply pipe 23A. Multiple branch pipes 27 are branched and connected to the connecting pipe 26A. Each of the multiple branch pipes 27 communicates the connecting pipe 26A with the gas phase in each tank 10. Each of the multiple branch pipes 27 is provided with a valve (not shown) to interrupt the flow of carbon dioxide through the branch pipe 27.

[0025] The inert gas supply unit 22A is configured to supply carbon dioxide recovered in the carbon dioxide recovery unit 21 as inert gas G to each of the multiple tanks 10 by opening the on / off valve 231 and the valves (not shown) of each of the multiple branch pipes 27. At this time, carbon dioxide is supplied to the tanks 10 only through the branch pipes 27 with open valves, and not through the branch pipes 27 with closed valves. In other words, by individually opening and closing the valves of each of the multiple branch pipes 27, it is possible to select which tanks 10 will receive carbon dioxide and which will not receive carbon dioxide from among the multiple tanks 10.

[0026] The carbon dioxide discharge unit 50 discharges the gaseous phase gas from the tank 10 to the outside of the ship 1. The carbon dioxide discharge unit 50 in this embodiment includes a discharge pipe 51 and an on-off valve 52. One end of the discharge pipe 51 is connected to the connecting pipe 26A. The other end of the discharge pipe 51 is connected to a bunker station (not shown), and through this bunker station, it is possible to connect to offshore facilities such as a storage facility 200 (see Figure 5) and a supply facility 300 (see Figure 7) outside the ship 1. The on-off valve 52 intermittently discharges the gas through the discharge pipe 51.

[0027] The gas in the gas phase of tank 10 can be discharged to the outside of the ship 1 via the carbon dioxide discharge section 50 by, for example, opening the on / off valve 52 and opening the valve (not shown) of the branch pipe 27. At this time, the gas in tank 10 can only be discharged through the branch pipe 27 with the valve opened among the multiple branch pipes 27. In other words, by individually opening and closing the valves of the multiple branch pipes 27, it is possible to select which tanks 10 will discharge the gas phase and which will not discharge the gas phase from among the multiple tanks 10.

[0028] (Procedure for supplying inert gas) Figure 3 is a flowchart showing the procedure of an inert gas supply method according to an embodiment of this disclosure. As shown in Figure 3, the inert gas supply method S10 according to the embodiment of this disclosure includes a step S11 for recovering carbon dioxide and a step S12 for supplying carbon dioxide to a tank 10.

[0029] In the carbon dioxide recovery process S11, the carbon dioxide recovery unit 21 recovers carbon dioxide contained in the exhaust gas from the combustion device 9 that burns the fuel.

[0030] In step S12, which involves supplying carbon dioxide to tank 10, the recovered carbon dioxide is supplied to tank 10 as inert gas G. This is done by opening the on-off valve 231 in the inert gas supply unit 22A, as well as opening the valves (not shown) of each of the multiple branch pipes 27. As a result, the carbon dioxide recovered in the carbon dioxide recovery unit 21 is supplied as inert gas G from the carbon dioxide recovery unit 21 to the gas phase of each of the multiple tanks 10.

[0031] (Supply of inert gas during navigation) Figure 4 shows the inert gas supply status during a ship's navigation. As shown in Figure 4, when the ship 1 is sailing with liquid L loaded in tank 10, the inert gas supply unit 22A fills the gas phase of each of the multiple tanks 10 with inert gas G using carbon dioxide recovered in carbon dioxide recovery unit 21.

[0032] During the navigation of vessel 1, the temperature inside tank 10 fluctuates due to the difference in temperature between day and night, and radiant heat from sunlight during the day. Along with the temperature fluctuations inside tank 10, the pressure inside tank 10 also fluctuates. In response to this, the inert gas supply unit 22A supplies carbon dioxide into tank 10 using the inert gas supply method S10 (in other words, replenishes it) to maintain the pressure inside tank 10 above a specified value, so that the pressure inside tank 10 does not fall below the pressure outside tank 10 and air from outside tank 10 is not drawn into tank 10.

[0033] (Supply of inert gas during unloading) Figure 5 shows the supply status of inert gas during cargo unloading from a ship. As shown in Figure 5, when a ship 1 unloads liquid L from a tank 10 to a storage facility 200 such as an onshore industrial complex that will receive the liquid L, such as crude oil or refined petroleum products, the connecting pipe 16 of the liquid piping section 15 is connected to the storage facility 200 via a bunkering station or the like. In this state, the on-off valve 16v of the connecting pipe 16 and the valve (not shown) of the branch pipe 17 connected to the tank 10 to be unloaded (tank 10D in the example of Figure 4) are opened, and the load handling pump of the branch pipe 17 is activated. As a result, the liquid L in the tank 10 is unloaded into the storage facility 200 through the liquid piping section 15. In this way, the unloading of the multiple tanks 10 is carried out sequentially.

[0034] As described above, when unloading liquid L from tank 10 to storage facility 200, the liquid level in tank 10 (tank 10D in the example of Figure 4) gradually decreases. The inert gas supply unit 22A supplies carbon dioxide into tank 10 in response to this decrease in liquid level using the inert gas supply method S10 described above. That is, the inert gas supply unit 22A supplies carbon dioxide as inert gas G to the gas phase of tank 10 (tank 10D in the example of Figure 4) in which liquid L is being unloaded. This is done by opening the on-off valve 231 and opening the valve (not shown) of the branch piping 27 of tank 10 (tank 10D in the example of Figure 4) in which the unloading is taking place. As a result, the amount of inert gas G stored in tank 10 can be increased in response to the decrease in liquid level in tank 10, thereby suppressing the pressure drop inside tank 10.

[0035] (Supply of inert gas during unloaded voyages) Figure 6 shows the inert gas supply status during unloaded ship navigation. As shown in Figure 6, when the tank 10 is empty after the unloading of liquid L has been completed, the tank 10 is filled with carbon dioxide as inert gas G. When the ship 1 sails empty toward a supply facility 300 (see Figure 7) that will be the source of liquid L such as crude oil or refined petroleum products in order to load new liquid L into the tank 10, the state in which the tank 10 is filled with carbon dioxide as inert gas G is maintained. In this case as well, while the vessel 1 is in transit, the inert gas supply unit 22A supplies carbon dioxide into the tank 10 using the inert gas supply method S10 to maintain the pressure inside the tank 10 above a specified value, so that the pressure inside the tank 10 does not fall below the pressure outside the tank 10 due to temperature fluctuations inside the tank 10 caused by the difference in temperature between day and night, and radiant heat from sunlight during the day.

[0036] (Supply of inert gas during loading) Figure 7 shows the discharge state of inert gas during loading of a ship. As shown in Figure 7, when ship 1 loads liquid L into tank 10 from a supply facility 300 which is the source of liquid L such as crude oil or refined petroleum products, the connecting pipe 16 of the liquid piping section 15 is connected to the supply facility 300 outside ship 1 via a bunker station (not shown), etc. In this state, the on-off valve 16v of the connecting pipe 16 and the valve (not shown) of the branch pipe 17 are opened, and the pump (not shown) on the supply facility 300 side is activated. As a result, liquid L is loaded into the tank 10 from the supply facility 300 through the liquid piping section 15.

[0037] In this manner, when loading liquid L from the supply facility 300 into the tank 10, the other end of the discharge pipe 51 is connected to the supply facility 300 via a bunker station (not shown). Then, the shut-off valve 52 of the discharge pipe 51 is opened, and the valve (not shown) of the branch pipe 27 connected to the tank 10 into which the liquid L is being loaded is also opened. As the amount of liquid L stored in the tank 10 increases, the liquid level in the tank 10 gradually rises, and the gas in the gas phase of the tank 10, i.e., the inert gas G filled in the tank 10, is pushed out of the tank 10. The pushed-out carbon dioxide is discharged to the supply facility 300 through the carbon dioxide discharge section 50.

[0038] Here, the supply facility 300 may also send the gaseous phase gas (in other words, inert gas G, carbon dioxide) from tank 10 discharged from ship 1 as inert gas G to a tank (not shown) that was storing liquid L in the supply facility 300. Furthermore, if the supply facility 300 is connected to an oil field 301 from which crude oil is extracted, the gaseous phase gas from tank 10 discharged from ship 1 may be sent to the oil field 301.

[0039] (Effects and Benefits) In the inert gas supply system 20A, ship 1, and inert gas supply method S10 of the first embodiment described above, carbon dioxide contained in the exhaust gas from the combustion device 9 that burns fuel is recovered, and the recovered carbon dioxide is supplied to the tank 10 as inert gas G. By utilizing the carbon dioxide contained in the exhaust gas as inert gas G in this way, carbon dioxide is utilized effectively, and there is no need to use other inert gases as inert gas G. Therefore, the need to drive engines, boilers, fans, etc. to supply the inert gas used as inert gas G into the tank 10 is reduced. Consequently, the energy consumption of the inert gas supply system 20A can be reduced, the energy consumption of the ship 1, which has limited available energy, can be reduced, and greenhouse gas emissions can be reduced.

[0040] Furthermore, in the first embodiment described above, carbon dioxide is supplied into the tank 10 so that the pressure inside the tank 10 does not fall below the pressure outside the tank 10 due to fluctuations in ambient temperature. This makes it possible to fill the gas phase inside the tank 10 with carbon dioxide as an inert gas G while suppressing a decrease in the pressure of the gas phase inside the tank 10.

[0041] Furthermore, in the first embodiment described above, when crude oil or refined petroleum products are loaded from the supply facility 300 into the tank 10, the carbon dioxide stored in the tank 10 is sent to the supply facility 300 through the carbon dioxide discharge unit 50. This allows the carbon dioxide contained in the exhaust gas of the combustion device 9, which is recovered during the navigation of the ship 1, to be recovered by the supply facility 300 without being released into the atmosphere. The supply facility 300 can then fill the tanks of the supply facility 300 with inert gas G or fill the oil field 301 with the recovered carbon dioxide, thereby reducing the amount of inert gas and carbon dioxide used by the supply facility 300.

[0042] <Second Embodiment> Next, a second embodiment of the inert gas supply system, vessel, and inert gas supply method according to this disclosure will be described. In the second embodiment described below, only the configuration of the inert gas supply system differs from the first embodiment, so the same parts as in the first embodiment will be denoted by the same reference numerals and described with reference to Figures 1 and 3, and redundant explanations will be omitted. Figure 8 shows the configuration of an inert gas supply system according to the second embodiment of this disclosure. As shown in Figure 8, the inert gas supply system 20B provided on the ship 1 of this embodiment is capable of supplying inert gas G to the tank 10. The inert gas supply system 20B comprises at least a carbon dioxide recovery unit 21, an inert gas supply unit 22B, and a carbon dioxide discharge unit 50.

[0043] The inert gas supply unit 22B supplies the carbon dioxide recovered in the carbon dioxide recovery unit 21 to the tank 10 as inert gas G. In the second embodiment of this disclosure, the inert gas supply unit 22B includes a carbon dioxide supply pipe 23B, a carbon dioxide storage unit 30B, and a piping unit 24B.

[0044] The carbon dioxide storage unit 30B stores the carbon dioxide recovered by the carbon dioxide recovery unit 21. The carbon dioxide storage unit 30B of the second embodiment of this disclosure comprises a compressor 31 and a gaseous carbon dioxide storage tank 32.

[0045] The compressor 31 is connected to the carbon dioxide recovery unit 21 via a connecting pipe 35. The compressor 31 compresses the carbon dioxide recovered in the carbon dioxide recovery unit 21. The carbon dioxide compressed by the compressor 31 is sent to the gaseous carbon dioxide storage tank 32 through a connecting pipe 37.

[0046] The gaseous carbon dioxide storage tank 32 stores the carbon dioxide compressed by the compressor 31 in a gaseous state. The gaseous carbon dioxide storage tank 32 is connected to the piping section 24B via the carbon dioxide supply pipe 23B. An on-off valve 232 is provided in the middle of the carbon dioxide supply pipe 23B. The on-off valve 232 intermittently supplies carbon dioxide from the gaseous carbon dioxide storage tank 32 to the multiple tanks 10 through the carbon dioxide supply pipe 23B.

[0047] The piping section 24B includes a connecting pipe 26B and a plurality of branch pipes 27. The connecting pipe 26B is connected to the carbon dioxide supply pipe 23B. The plurality of branch pipes 27 are provided branching off from the connecting pipe 26B.

[0048] The inert gas supply unit 22B is configured to supply carbon dioxide stored in the gaseous carbon dioxide storage tank 32 as inert gas G to each of the tanks 10 by opening the on / off valve 232 and the valves (not shown) of the branch pipes 27 connected to each of the tanks 10.

[0049] The carbon dioxide discharge unit 50 comprises a discharge pipe 51 and an on-off valve 52. One end of the discharge pipe 51 is connected to a connecting pipe 26B. The other end of the discharge pipe 51 is connectable to external facilities such as a storage facility 200 (see Figure 10) and a supply facility 300 (see Figure 12) outside the ship 1 via a bunker station (not shown). An on-off valve 52 is provided in the middle of the discharge pipe 51. The on-off valve 52 intermittently discharges carbon dioxide through the discharge pipe 51.

[0050] (Procedure for supplying inert gas) As shown in Figure 3, the inert gas supply method S20 according to the embodiment of this disclosure includes a step S21 for recovering carbon dioxide and a step S22 for supplying carbon dioxide to the tank 10.

[0051] In carbon dioxide recovery step S21, the carbon dioxide recovery unit 21 recovers the carbon dioxide contained in the exhaust gas of the combustion device 9. In carbon dioxide recovery step S21, the carbon dioxide recovered by the carbon dioxide recovery unit 21 is further compressed by the compressor 31 and then stored in the gaseous carbon dioxide storage tank 32.

[0052] In step S22, which involves supplying carbon dioxide to tank 10, the recovered carbon dioxide is supplied to tank 10 as inert gas G. This is done by opening the on-off valve 232 in the inert gas supply unit 22B, as well as opening the valves (not shown) of each of the multiple branch pipes 27. As a result, the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 is supplied as inert gas G from the carbon dioxide recovery unit 21 to the gas phase of each of the multiple tanks 10.

[0053] (Supply of inert gas during navigation) Figure 9 shows the inert gas supply status while a ship is in motion. As shown in Figure 9, when the ship 1 is in motion with liquid L loaded in tank 10, the inert gas supply unit 22B fills the gas phase of each of the multiple tanks 10 with inert gas G, using carbon dioxide recovered in the carbon dioxide recovery unit 21.

[0054] Furthermore, while the vessel 1 is underway, step S21 of the inert gas supply method S20 described above is executed, and the carbon dioxide recovered from the exhaust gas of the combustion device 9 is stored in the gaseous carbon dioxide storage tank 32.

[0055] If, while the vessel 1 is in transit, the pressure inside the tank 10 falls below the pressure outside the tank 10 due to fluctuations in the outside temperature, the inert gas supply unit 22B executes step S22 of the inert gas supply method S20 described above, and supplies carbon dioxide stored in the gaseous carbon dioxide storage tank 32 into the tank 10.

[0056] (Supply of inert gas during unloading) Figure 10 shows the supply status of inert gas during cargo unloading from a ship. As shown in Figure 10, when the ship 1 unloads the liquid L from the tank 10 to a storage facility 200 located on land, the connecting pipe 16 of the liquid piping section 15 is connected to the storage facility 200. In this state, the shut-off valve 16v of the connecting pipe 16 and the valve (not shown) of the branch pipe 17 are opened, and the load handling pump of the branch pipe 17 is activated. As a result, the liquid L in the tank 10 is unloaded into the storage facility 200 through the liquid piping section 15. Thus, when unloading the liquid L from tank 10 to the storage facility 200, the inert gas supply unit 22B executes step S22 of the inert gas supply method S20 described above to tank 10 from which the liquid L is being unloaded, supplying carbon dioxide stored in gaseous carbon dioxide storage tank 32 as inert gas G. As a result, as the amount of liquid L in tank 10 decreases, the amount of inert gas G stored in tank 10 increases, and the pressure inside tank 10 can be maintained.

[0057] (Supply of inert gas during unloaded voyages) Figure 11 shows the inert gas supply status during unloaded ship navigation. As shown in Figure 11, when the tank 10 is empty after the unloading of liquid L has been completed, the tank 10 is filled with carbon dioxide as inert gas G. When the vessel 1 sails empty toward the supply facility 300 to load new liquid L into the tank 10, the state in which the tank 10 is filled with carbon dioxide as inert gas G is maintained. In this case as well, if, while the ship 1 is sailing, the pressure inside the tank 10 falls below the pressure outside the tank 10 due to temperature fluctuations inside the tank 10, the inert gas supply unit 22B executes process S22 and supplies carbon dioxide stored in the gaseous carbon dioxide storage tank 32 into the tank 10.

[0058] (Supply of inert gas during loading) Figure 12 shows the discharge status of inert gas during ship loading. As shown in Figure 12, when loading liquid L from the supply facility 300 into tank 10, the other end of the discharge pipe 51 is connected to the supply facility 300 via a bunker station (not shown). Then, the shut-off valve 52 of the discharge pipe 51 is opened, and at the tank 10 (tank 10D in the example of Figure 4) into which liquid L is being loaded, the valve (not shown) of the branch pipe 27 is opened. As the amount of liquid L stored in tank 10 increases, the gas phase gas in tank 10, i.e., the inert gas G filled in tank 10, is pushed out of tank 10. The pushed-out carbon dioxide is discharged to the supply facility 300 through the carbon dioxide discharge section 50.

[0059] Figure 13 is another diagram showing the inert gas discharge conditions on a ship. As shown in Figure 13, before and after loading liquid L from the supply facility 300 into the tank 10, the valve (not shown) of the branch pipe 27 may be closed and the shut-off valve 232 may be opened. In this way, the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 is discharged to the supply facility 300 through the carbon dioxide discharge section 50.

[0060] Here, the supply facility 300 may also send the gaseous phase gas (in other words, inert gas G, carbon dioxide) from the tank 10 discharged from the ship 1 as inert gas G to the tank (not shown) that was storing liquid L in the supply facility 300. Furthermore, if the supply facility 300 is connected to an oil field 301 from which crude oil is extracted, the carbon dioxide discharged from the ship 1 may be sent to the oil field 301.

[0061] (Effects and Benefits) In the inert gas supply system 20B, ship 1, and inert gas supply method S20 of the second embodiment described above, energy consumption by the inert gas supply system 20B can be reduced, and greenhouse gas emissions can be reduced, similar to the first embodiment described above.

[0062] Furthermore, in the second embodiment described above, a carbon dioxide storage unit 30B is provided for storing the carbon dioxide recovered by the carbon dioxide recovery unit 21. This allows the inert gas supply unit 22B to supply the carbon dioxide stored in the carbon dioxide storage unit 30B to the tank 10 as inert gas G. This allows carbon dioxide contained in the exhaust gas from the combustion device 9 to be stored in the carbon dioxide storage unit 30B, and carbon dioxide to be supplied from the carbon dioxide storage unit 30B to the tank 10 at an appropriate timing as needed, regardless of the operating state of the combustion device 9. This makes it possible to recover carbon dioxide contained in the exhaust gas while effectively utilizing the recovered carbon dioxide.

[0063] Furthermore, in the second embodiment described above, the carbon dioxide compressed by the compressor 31 is stored in a gaseous state in the gaseous carbon dioxide storage tank 32. This allows for the efficient recovery and storage of carbon dioxide contained in the exhaust gas. Then, at the appropriate time, carbon dioxide can be supplied from the gaseous carbon dioxide storage tank 32 to the tank 10. At this time, since the carbon dioxide in the gaseous carbon dioxide storage tank 32 is in a gaseous state, it is possible to supply carbon dioxide to the tank 10 more quickly compared to the case where carbon dioxide is stored in liquefaction, because there is no need to vaporize it.

[0064] <Third Embodiment> Next, a third embodiment of the inert gas supply system, vessel, and inert gas supply method according to this disclosure will be described. In the third embodiment described below, only the configuration of the inert gas supply system differs from the first embodiment, so the same parts as in the first embodiment will be denoted by the same reference numerals and the explanation will be given with reference to Figures 1 and 3, and redundant explanations will be omitted. Figure 14 shows the configuration of an inert gas supply system according to the third embodiment of this disclosure. As shown in Figure 14, the inert gas supply system 20C provided on the ship 1 of this embodiment is capable of supplying inert gas G to the tank 10. The inert gas supply system 20C comprises at least a carbon dioxide recovery unit 21, an inert gas supply unit 22C, and a carbon dioxide discharge unit 50.

[0065] The inert gas supply unit 22C supplies carbon dioxide recovered in the carbon dioxide recovery unit 21 to the tank 10 as inert gas G. The inert gas supply unit 22C of the third embodiment of this disclosure comprises a carbon dioxide storage unit 30C, two carbon dioxide supply pipes 23B and 23C, and a piping unit 24C.

[0066] The carbon dioxide storage unit 30C stores the carbon dioxide recovered in the carbon dioxide recovery unit 21. In the third embodiment of this disclosure, the carbon dioxide storage unit 30C comprises a compressor 31, a gaseous carbon dioxide storage tank 32, a liquefaction unit 33, and a liquid carbon dioxide storage tank 34.

[0067] The compressor 31 is connected to the carbon dioxide recovery unit 21 via a connecting pipe 35. The compressor 31 compresses the carbon dioxide recovered in the carbon dioxide recovery unit 21. A portion of the carbon dioxide compressed by the compressor 31 is sent to the gaseous carbon dioxide storage tank 32 through a connecting pipe 37. The remaining carbon dioxide compressed by the compressor 31 is sent to the liquefaction unit 33 through a connecting pipe 38. The destination of the carbon dioxide discharged from the compressor 31 may be selectable between the gaseous carbon dioxide storage tank 32 and the liquefaction unit 33, for example, by using multiple valves (not shown).

[0068] The gaseous carbon dioxide storage tank 32 stores the carbon dioxide compressed by the compressor 31 in a gaseous state. The gaseous carbon dioxide storage tank 32 is connected to the piping section 24C via the carbon dioxide supply pipe 23B. An on-off valve 232 is provided in the middle of the carbon dioxide supply pipe 23B. The on-off valve 232 intermittently supplies carbon dioxide from the gaseous carbon dioxide storage tank 32 to the multiple tanks 10 through the carbon dioxide supply pipe 23B.

[0069] The liquefaction unit 33 liquefies the carbon dioxide compressed by the compressor 31. A refrigerator can be an example of the liquefaction unit 33. The liquefaction unit 33 sends the liquefied carbon dioxide to the liquid carbon dioxide storage tank 34 through the connecting pipe 39.

[0070] The liquid carbon dioxide storage tank 34 stores the carbon dioxide liquefied in the liquefaction section 33 in a liquid state. The liquid carbon dioxide storage tank 34 is connected to the piping section 24C via the carbon dioxide supply pipe 23C. An on-off valve 233 is provided in the middle of the carbon dioxide supply pipe 23C. The on-off valve 233 intermittently supplies carbon dioxide from the liquid carbon dioxide storage tank 34 to the multiple tanks 10 through the carbon dioxide supply pipe 23C. A vaporization section (not shown) is provided in the middle of the carbon dioxide supply pipe 23C. The vaporization section vaporizes the liquefied carbon dioxide sent from the liquid carbon dioxide storage tank 34. An example of the vaporization section is a heat exchanger, and an example of the heat transfer medium in the vaporization section is an antifreeze heated by steam or the like. As a result, the carbon dioxide vaporized through the vaporization section is supplied to each tank 10.

[0071] The piping section 24C includes a connecting pipe 26C and a plurality of branch pipes 27. The connecting pipe 26C is connected to the carbon dioxide supply pipe 23B and the carbon dioxide supply pipe 23C. The plurality of branch pipes 27 each branch off from the connecting pipe 26C.

[0072] The inert gas supply unit 22C can vaporize the carbon dioxide stored in the liquid carbon dioxide storage tank 34 and then supply it as inert gas G to each of the multiple tanks 10 by opening the on-off valve 233 and the valves (not shown) of the branch pipes 27. Also, similar to the inert gas supply unit 22B in the second embodiment described above, the inert gas supply unit 22C can supply the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 as inert gas G to each of the multiple tanks 10 by opening the on-off valve 232 and the valves (not shown) of the multiple branch pipes 27.

[0073] (Procedure for supplying inert gas) As shown in Figure 3, the inert gas supply method S30 according to the embodiment of this disclosure includes a step S31 for recovering carbon dioxide and a step S32 for supplying carbon dioxide to the tank 10.

[0074] In carbon dioxide recovery process S31, the carbon dioxide recovery unit 21 recovers the carbon dioxide contained in the exhaust gas of the combustion device 9. In carbon dioxide recovery process S31, the carbon dioxide recovered by the carbon dioxide recovery unit 21 is compressed by the compressor 31, and a portion of it is stored in the gaseous carbon dioxide storage tank 32. In carbon dioxide recovery process S31, the carbon dioxide recovered by the carbon dioxide recovery unit 21 is compressed by the compressor 31, and the remainder is liquefied by the liquefaction unit 33 and stored in the liquid carbon dioxide storage tank 34.

[0075] In step S32, which involves supplying carbon dioxide to tank 10, the recovered carbon dioxide is supplied to tank 10 as inert gas G. This is done by opening the on-off valve 233 at the inert gas supply unit 22C, as well as opening each of the valves (not shown) in the multiple branch pipes 27. As a result, the carbon dioxide stored in the liquid carbon dioxide storage tank 34 is vaporized and then supplied as inert gas G from the carbon dioxide recovery unit 21 to each gas phase of the multiple tanks 10. Alternatively, the on-off valve 232 at the inert gas supply unit 22C is opened, as well as opening each of the valves (not shown) in the multiple branch pipes 27. This allows the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 to be supplied as inert gas G to each gas phase of the multiple tanks 10.

[0076] (Supply of inert gas during navigation) Figure 15 shows the inert gas supply status during a ship's navigation. As shown in Figure 15, when the ship 1 is sailing with liquid L loaded in tank 10, the inert gas supply unit 22C fills the gas phases of the multiple tanks 10 with inert gas G using carbon dioxide recovered in carbon dioxide recovery unit 21.

[0077] Furthermore, while the vessel 1 is underway, step S31 of the inert gas supply method S30 described above is executed to store the carbon dioxide recovered from the exhaust gas of the combustion device 9 in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34, respectively.

[0078] While the vessel 1 is sailing, if the pressure inside the tank 10 falls below the pressure outside the tank 10 due to the temperature difference between day and night, radiant heat from sunlight during the day, etc., the inert gas supply unit 22C will supply carbon dioxide stored in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34 as inert gas G into the tank 10 according to step S32 of the inert gas supply method S30 described above.

[0079] (Supply of inert gas during unloading) Figure 16 shows the inert gas supply status during cargo unloading from a ship. As shown in Figure 16, when ship 1 unloads liquid L from tank 10 to storage facility 200 located on land, the connecting pipe 16 of the liquid piping section 15 is connected to the storage facility 200. In this state, the shut-off valve 16v of the connecting pipe 16 and the valve (not shown) of the branch pipe 17 are opened, and the load handling pump of the branch pipe 17 is activated. As a result, the liquid L in the tank 10 is unloaded into the storage facility 200 through the liquid piping section 15.

[0080] Thus, when unloading liquid L from tank 10 to storage facility 200, the inert gas supply unit 22C executes step S32 of the inert gas supply method S30 described above to tank 10 from which liquid L is being unloaded. As a result, carbon dioxide stored in gaseous carbon dioxide storage tank 32 and liquid carbon dioxide storage tank 34 is supplied to tank 10 from which unloading is taking place (tank 10D in the example of Figure 16). Therefore, as the amount of liquid L in tank 10 decreases (in other words, the liquid level drops), the amount of inert gas G stored in tank 10 is increased, and the pressure inside tank 10 can be maintained.

[0081] (Supply of inert gas during unloaded voyages) Figure 17 shows the inert gas supply status during unloaded ship navigation. As shown in Figure 17, when the tank 10 is empty after the unloading of liquid L has been completed, the tank 10 is filled with carbon dioxide as inert gas G. When the vessel 1 sails empty toward the supply facility 300 to load new liquid L into the tank 10, the state in which the tank 10 is filled with carbon dioxide as inert gas G is maintained. In this case as well, if, while the vessel 1 is sailing, the pressure inside the tank 10 falls below the pressure outside the tank 10 due to the temperature difference between day and night, radiant heat from sunlight during the day, etc., the inert gas supply unit 22C executes step S32 of the inert gas supply method S30 described above. As a result, carbon dioxide stored in the liquid carbon dioxide storage tank 34 is supplied into the tank 10.

[0082] (Supply of inert gas during loading) Figure 18 shows the discharge status of inert gas during ship loading. As shown in Figure 18, when loading liquid L from the supply facility 300 into tank 10, the other end of the discharge pipe 51 is connected to the supply facility 300 via a bunker station (not shown). Then, the shut-off valve 52 of the discharge pipe 51 is opened, and at the tank 10 (tank 10D in the example of Figure 18) into which liquid L is being loaded, the valve (not shown) of the branch pipe 27 is opened. As the amount of liquid L stored in tank 10 increases, the gas in the gas phase of tank 10, i.e., the inert gas G filled in tank 10, is pushed out of tank 10. The pushed-out carbon dioxide is discharged to the supply facility 300 through the carbon dioxide discharge section 50.

[0083] Figure 19 is another diagram showing the inert gas discharge conditions on a ship. As shown in Figure 19, before and after loading liquid L from the supply facility 300 into the tank 10, the valve (not shown) of the branch pipe 27 may be closed and the shut-off valves 232 and 233 may be opened. In this way, the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34 is discharged to the supply facility 300 through the carbon dioxide discharge section 50.

[0084] Here, the supply facility 300 may, as in the embodiments described above, send the gas phase gas (in other words, inert gas G, carbon dioxide) from the tank 10 discharged from the ship 1 as inert gas G to the tank (not shown) that was storing liquid L in the supply facility 300. Also, if the supply facility 300 is connected to an oil field 301 from which crude oil is extracted, the carbon dioxide discharged from the ship 1 may be sent to the oil field 301.

[0085] (Effects and Benefits) In the inert gas supply system 20C, ship 1, and inert gas supply method S30 of the third embodiment described above, energy consumption by the inert gas supply system 20C can be reduced, and greenhouse gas emissions can be reduced, similar to the first and second embodiments described above.

[0086] Furthermore, in the third embodiment described above, a carbon dioxide storage unit 30C is provided for storing the carbon dioxide recovered by the carbon dioxide recovery unit 21. As a result, the inert gas supply unit 22C can supply the carbon dioxide stored in the carbon dioxide storage unit 30C to the tank 10 as inert gas G. Therefore, carbon dioxide contained in the exhaust gas of the combustion device 9 can be stored in the carbon dioxide storage unit 30C, and carbon dioxide can be supplied from the carbon dioxide storage unit 30C to the tank 10 as inert gas G at an appropriate timing as needed. Thus, carbon dioxide contained in the exhaust gas can be recovered, and the recovered carbon dioxide can be effectively utilized.

[0087] Furthermore, in the third embodiment described above, since the carbon dioxide liquefied in the liquefaction unit 33 is stored in liquid form in the liquid carbon dioxide storage tank 34, more carbon dioxide can be stored without expanding the storage space compared to the case where it is stored as a gas. Therefore, it is possible to store more carbon dioxide in the limited space of the ship 1. In addition, carbon dioxide can be supplied from the liquid carbon dioxide storage tank 34 to the tank 10 as inert gas G at an appropriate timing.

[0088] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure. For example, in the second and third embodiments described above, the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34 is discharged to the supply facility 300, but this is not limited to this. The carbon dioxide stored in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34 may be discharged to a carbon dioxide recovery facility installed in a port or the like. Furthermore, although the case where the supply facility 300 is installed on land has been described, the supply facility 300 may also be installed on another vessel. Furthermore, in the third embodiment described above, it is also possible to have a configuration that does not include a gaseous carbon dioxide storage tank 32.

[0089] Furthermore, the configuration of the first embodiment may be combined with the second and third embodiments described above. More specifically, the configuration of the second and third embodiments may be modified to include a setting in which carbon dioxide recovered by the carbon dioxide recovery unit 21 is directly sent to the tank 10 through the carbon dioxide supply pipe 23A, as in the first embodiment described above.

[0090] Furthermore, while the above embodiments describe cases in which carbon dioxide recovered by the ship 1 is supplied to the tanks of the supply facility 300, the oil field 301, etc., the invention is not limited to this. The supply facility 300 may also use the recovered carbon dioxide and materials obtained from crude oil to produce products such as methane and methanol.

[0091] <Note> The inert gas supply systems 20A to 20C, the ship 1, and the inert gas supply methods S10, S20, and S30 described in each embodiment can be understood, for example, as follows.

[0092] (1) The inert gas supply systems 20A to 20C according to the first embodiment are inert gas supply systems 20A to 20C installed on a ship 1 and capable of supplying inert gas G to a tank 10 capable of storing crude oil or petroleum refined products, comprising: a carbon dioxide recovery unit 21 that recovers carbon dioxide contained in exhaust gas from a combustion device 9 that burns fuel; and inert gas supply units 22A to 22C that supply the carbon dioxide recovered by the carbon dioxide recovery unit 21 as inert gas G to the tank 10. Examples of combustion devices 9 include internal combustion engines and boilers. Examples of petroleum products include gasoline, kerosene, naphtha, and methanol.

[0093] This inert gas supply system 20A-20C recovers carbon dioxide contained in the exhaust gas from the combustion device 9 that burns fuel, and supplies the recovered carbon dioxide as inert gas G to the tank 10. In this way, by utilizing the carbon dioxide contained in the exhaust gas as inert gas G, carbon dioxide is utilized effectively, eliminating the need to use other inert gases as inert gas G. Therefore, the need to drive the engine, boiler, fan, etc. to supply the inert gas used as inert gas G into the tank 10 is reduced. Consequently, the energy such as fuel required to drive the engine, boiler, fan, etc. to supply inert gas G to the tank 10 is not needed. Therefore, in a ship 1 where available energy is limited, energy consumption can be reduced, and greenhouse gas emissions can be reduced.

[0094] (2) The inert gas supply system 20B, 20C according to the second embodiment is the inert gas supply system 20B, 20C of (1), further comprising carbon dioxide storage units 30B, 30C for storing the carbon dioxide recovered in the carbon dioxide recovery unit 21, and the inert gas supply units 22B, 22C supply the carbon dioxide stored in the carbon dioxide storage units 30B, 30C as inert gas G to the tank 10.

[0095] In this configuration, by providing carbon dioxide storage units 30B and 30C for storing the carbon dioxide recovered by the carbon dioxide recovery unit 21, the inert gas supply units 22B and 22C can supply the carbon dioxide stored in the carbon dioxide storage units 30B and 30C to the tank 10 as inert gas G. This allows carbon dioxide contained in the exhaust gas from the combustion device 9 to be stored in the carbon dioxide storage units 30B and 30C, and then supplied from the carbon dioxide storage units 30B and 30C to the tank 10 at the appropriate time as needed. This makes it possible to recover carbon dioxide contained in the exhaust gas while effectively utilizing the recovered carbon dioxide.

[0096] (3) The inert gas supply system 20B, 20C according to the third embodiment is the inert gas supply system 20B, 20C of (2), wherein the carbon dioxide storage section 30B, 30C comprises a compressor 31 for compressing the carbon dioxide and a gaseous carbon dioxide storage tank 32 for storing the carbon dioxide compressed by the compressor 31 in a gaseous state.

[0097] This allows the carbon dioxide compressed by the compressor 31 to be stored in a gaseous state in the gaseous carbon dioxide storage tank 32, thereby efficiently recovering and storing the carbon dioxide contained in the exhaust gas. Then, at the appropriate time, the carbon dioxide can be sent from the gaseous carbon dioxide storage tank 32 to the tank 10. At this time, since the carbon dioxide in the gaseous carbon dioxide storage tank 32 is in a gaseous state, there is no need to vaporize it compared to when the carbon dioxide is liquefied, and the carbon dioxide can be sent to the tank 10 more quickly.

[0098] (4) An inert gas supply system 20C according to a fourth embodiment is an inert gas supply system 20C according to (2) or (3), wherein the carbon dioxide storage unit 30C comprises a liquefaction unit 33 for liquefying the carbon dioxide and a liquid carbon dioxide storage tank 34 for storing the carbon dioxide liquefied in the liquefaction unit 33.

[0099] This allows the carbon dioxide liquefied in the liquefaction unit 33 to be stored in liquid form in the liquid carbon dioxide storage tank 34, enabling the storage of more carbon dioxide in a limited space. Furthermore, carbon dioxide can be supplied from the liquid carbon dioxide storage tank 34 at the appropriate time.

[0100] (5) The inert gas supply system 20B, 20C according to the fifth embodiment is any one of the inert gas supply systems 20B, 20C of (2) to (4), wherein the inert gas supply unit 22B, 22C supplies the carbon dioxide stored in the carbon dioxide storage unit 30B, 30C to the gas phase in the tank 10 as the level of the liquid phase in the tank 10 decreases when the crude oil or petroleum refined product is being discharged from the tank 10 to the outside of the tank 10.

[0101] As a result, when crude oil or refined petroleum products are being discharged from tank 10 to the outside of tank 10, carbon dioxide stored in the carbon dioxide storage unit 30B is supplied to the gas phase inside tank 10 as the level of the liquid phase inside tank 10 decreases. This makes it possible to maintain a state in which the gas phase inside tank 10 is filled with carbon dioxide. Furthermore, after the crude oil or refined petroleum products have been discharged to the outside of tank 10, the entire contents of tank 10 can be filled with carbon dioxide.

[0102] (6) The inert gas supply system 20A to 20C according to the sixth embodiment is any one of the inert gas supply systems 20A to 20C of (1) to (5), wherein the inert gas supply unit 22A to 22C supplies carbon dioxide into the tank 10 when the pressure inside the tank 10 falls below the pressure outside the tank 10 due to fluctuations in ambient temperature.

[0103] As a result, when the pressure inside the tank 10 falls below the pressure outside the tank 10 due to fluctuations in the outside temperature, carbon dioxide is supplied into the tank 10, thereby filling the gas phase inside the tank 10 with carbon dioxide while suppressing a decrease in the pressure of the gas phase inside the tank 10.

[0104] (7) An inert gas supply system 20A to 20C according to the seventh embodiment is any one of the inert gas supply systems 20A to 20C of (1) to (6), further comprising a carbon dioxide discharge unit 50 for discharging the carbon dioxide stored in the tank 10 to the outside of the ship 1, wherein when loading crude oil or refined petroleum products into the tank 10 from the crude oil or refined petroleum product supply facility 300 located outside the ship 1, the carbon dioxide stored in the tank 10 is sent to the supply facility 300 through the carbon dioxide discharge unit 50.

[0105] With this configuration, when crude oil or refined petroleum products are loaded from the crude oil or refined petroleum product supply facility 300 into the tank 10, the carbon dioxide stored in the tank 10 is sent to the supply facility 300 through the carbon dioxide discharge unit 50. This reduces the release of carbon dioxide contained in the exhaust gas from the combustion device 9, which is recovered during the navigation of the ship 1, into the atmosphere, and allows it to be recovered at the supply facility 300. The supply facility 300 can also fill the supply facility 300 where the crude oil or refined petroleum products loaded into the tank 10 of the ship 1 were stored, or the oil field from which the crude oil is extracted, with the recovered carbon dioxide as inert gas G. This reduces the need for the supply facility 300 to separately prepare inert gas to be used as inert gas G.

[0106] (8) The vessel 1 according to the eighth embodiment comprises a hull 2 ​​and one of the inert gas supply systems 20A to 20C from (1) to (7).

[0107] This reduces energy consumption on the vessel 1 and thus reduces greenhouse gas emissions.

[0108] (9) The inert gas supply methods S10, S20, and S30 according to the ninth embodiment are inert gas supply methods S10, S20, and S30 in any one of the inert gas supply systems 20A to 20C of (1) to (7), and include a step S11 of recovering carbon dioxide contained in the exhaust gas from a combustion device 9 that burns fuel, and a step S12 of supplying the recovered carbon dioxide as inert gas G to the tank 10.

[0109] This system recovers carbon dioxide from the exhaust gas from the combustion device 9 that burns the fuel, and supplies the recovered carbon dioxide as inert gas G to the tank 10. As a result, energy consumption can be reduced on the ship 1, and greenhouse gas emissions can be reduced. [Explanation of Symbols]

[0110] 1...Ship 2...Hull 2a...Bow 4...Superstructure 5A,5B...Side 6...Bottom 7...Upper deck 8...Cargo loading area 9...Combustion equipment 10,10A~10E...Tanks 15...Liquid piping section 16...Connecting piping 16v...On / off valve 17...Branch piping 20A~20C...Inert gas supply system 21...Carbon dioxide recovery section 22A~21C...Inert gas supply section 23A~23C...Carbon dioxide supply pipe 231~233...On / off valve 24A~24C...Piping section 26A~26C...Connecting piping 27...Branch piping 30B,30C...Carbon dioxide storage section 31...Compressor 32...Gaseous carbon dioxide storage tank 33...Liquefaction section 34...Liquid carbon dioxide storage tank 35,37,38,39...Connecting pipes 50…Carbon dioxide discharge section 51…Discharge piping 52…On / off valve 200…Storage facility 300…Supply facility 301…Oil field FA…Bow / stern direction G…Inert gas L…Liquid S10,S20,S30…Inert gas supply method S11,S21,S31…Process for recovering carbon dioxide S12,S22,S32…Process for supplying carbon dioxide to tanks

Claims

1. An inert gas supply system installed on a ship and capable of supplying inert gas to a tank capable of storing crude oil or petroleum refined products, A carbon dioxide recovery unit that recovers carbon dioxide contained in the exhaust gas from the combustion device that burns fuel, An inert gas supply unit supplies the carbon dioxide recovered in the carbon dioxide recovery unit to the tank as inert gas, A carbon dioxide storage unit for storing the carbon dioxide recovered in the carbon dioxide recovery unit, Equipped with, The inert gas supply unit is, When the crude oil or petroleum refined product is being discharged from the tank to the outside of the tank, the carbon dioxide stored in the carbon dioxide storage section is supplied to the gas phase in the tank as the level of the liquid phase in the tank decreases. Inert gas supply system.

2. An inert gas supply system installed on a ship and capable of supplying inert gas to a tank capable of storing crude oil or petroleum refined products, A carbon dioxide recovery unit that recovers carbon dioxide contained in the exhaust gas from the combustion device that burns fuel, An inert gas supply unit supplies the carbon dioxide recovered in the carbon dioxide recovery unit to the tank as inert gas, Equipped with, When the pressure inside the tank falls below the pressure outside the tank due to fluctuations in the outside temperature, carbon dioxide is supplied into the tank. Inert gas supply system.

3. The system further comprises a carbon dioxide storage unit for storing the carbon dioxide recovered in the carbon dioxide recovery unit, The inert gas supply unit supplies the carbon dioxide stored in the carbon dioxide storage unit to the tank as inert gas. The inert gas supply system according to claim 2.

4. The carbon dioxide storage unit is, A compressor for compressing the aforementioned carbon dioxide, The system includes a gaseous carbon dioxide storage tank for storing the carbon dioxide compressed by the compressor in a gaseous state. The inert gas supply system according to claim 1 or 3.

5. The carbon dioxide storage unit is, The liquefaction unit for liquefying the carbon dioxide, The system includes a liquid carbon dioxide storage tank for storing the carbon dioxide liquefied in the liquefaction unit. The inert gas supply system according to claim 1 or 3.

6. The vessel further comprises a carbon dioxide discharge unit for discharging the carbon dioxide stored in the tank to the outside of the vessel, When loading crude oil or refined petroleum products into the tank from the crude oil or refined petroleum product supply facility located outside the vessel, the carbon dioxide stored in the tank is sent back to the supply facility through the carbon dioxide discharge unit. The inert gas supply system according to claim 1 or 2.

7. The hull and, A tank provided on the hull of the ship, capable of storing crude oil or petroleum refined products, The inert gas supply system is as described in claim 1 or 2. ship.

8. An inert gas supply method in an inert gas supply system according to claim 1 or 2, A process for recovering carbon dioxide contained in exhaust gas from a combustion device that burns fuel, The process includes supplying the recovered carbon dioxide to the tank as an inert gas. Inert gas supply method.

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