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

Abstract

This inert gas supply system, which is provided on a ship and is capable of supplying an inert gas to a tank capable of storing crude oil or refined petroleum, is provided with: a carbon dioxide recovery unit that recovers carbon dioxide contained in exhaust gas from a combustion device that combusts fuel; and an inert gas supply unit for supplying the carbon dioxide recovered by the carbon dioxide recovery unit as an inert gas to the tank.

Description

Technical Field

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

[0002] This application claims the priority based on Japanese Patent Application No. 2022-198359 filed on December 13, 2022, and incorporates its content herein. Background Art

[0003] In a ship that transports volatile liquids such as crude oil or petroleum products, the volatile liquid is sometimes stored in a storage tank together with an inert gas (non-reactive gas).

[0004] In Patent Document 1, an inert gas supply system that supplies inert gas obtained by purifying exhaust gas from an engine or boiler for ship propulsion into a storage tank (cargo storage tank) of a ship is disclosed. The inert gas supply system includes an exhaust gas introduction flow path, an exhaust gas purification device, and an inert gas supply flow path. The exhaust gas introduction flow path 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 flow path supplies the inert gas generated by the exhaust gas purification device into the storage tank.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-193653 Summary of the Invention

[0008] Technical Problem to be Solved by the Invention

[0009] However, in the structure described in Patent Document 1, depending on the navigation conditions of the ship, etc., sometimes the engine or boiler is driven only to supply inert gas into the storage tank. And, in order to supply inert gas into the storage tank, it is necessary to drive a fan provided on the inert gas supply flow path. To drive such an engine, boiler, fan, etc., energy such as fuel is required. And, as a common problem in international maritime transportation, there are problems of reduction of greenhouse gases (GHG: Greenhouse Gas) typified by carbon dioxide (CO2), effective utilization and storage of carbon dioxide.

[0010] Therefore, in a ship, it is desired to reduce carbon dioxide emissions by suppressing energy consumption based on the inert gas supply system.

[0011] The present invention has been made to solve the above problems, and an object thereof is to provide an inert gas supply system, a ship, and an inert gas supply method capable of suppressing the emission of greenhouse gases.

[0012] Means for Solving Technical Problems

[0013] To solve the above problems, the inert gas supply system according to the present invention is an inert gas supply system capable of supplying inert gas to a storage tank provided on a ship and capable of storing crude oil or petroleum refined products. The inert gas supply system includes a carbon dioxide recovery unit and an inert gas supply unit. The carbon dioxide recovery unit recovers carbon dioxide contained in the exhaust gas from a combustion device that burns fuel. The inert gas supply unit supplies the carbon dioxide recovered by the carbon dioxide recovery unit to the storage tank as inert gas.

[0014] The ship according to the present invention includes a hull, a storage tank, and the above-mentioned inert gas supply system. The storage tank is provided on the hull. The storage tank is capable of storing crude oil or petroleum refined products.

[0015] The inert gas supply method according to the present invention is the inert gas supply method in the above-mentioned 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 storage tank. In the step of recovering carbon dioxide, carbon dioxide contained in the exhaust gas from a combustion device that burns fuel is recovered. In the step of supplying carbon dioxide to the storage tank, the recovered carbon dioxide is supplied to the storage tank as inert gas.

[0016] Advantages of the Invention

[0017] According to the inert gas supply system, ship, and inert gas supply method of the present invention, greenhouse gas emissions can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a side view of a floating body including the inert gas supply system, ship, and inert gas supply method according to an embodiment of the present invention.

[0019] Figure 2 is a diagram showing the structure of the inert gas supply system according to the first embodiment of the present invention.

[0020] Figure 3 is a flowchart showing the steps of the inert gas supply method according to each embodiment of the present invention.

[0021] Figure 4 is a diagram showing the supply state of inert gas during navigation of the ship according to the first embodiment of the present invention.

[0022] Figure 5 is a diagram showing the supply state of inert gas during unloading of the ship according to the first embodiment of the present invention.

[0023] Figure 6 This is a diagram showing the supply state of inert gas during the unloaded voyage of the ship according to the first embodiment of the present invention.

[0024] Figure 7 This is a diagram showing the discharge state of inert gas during the loading of the ship according to the first embodiment of the present invention.

[0025] Figure 8 This is a diagram showing the structure of the inert gas supply system according to the second embodiment of the present invention.

[0026] Figure 9 This is a diagram showing the supply state of inert gas during the voyage of the ship according to the second embodiment of the present invention.

[0027] Figure 10 This is a diagram showing the supply state of inert gas during the unloading of the ship according to the second embodiment of the present invention.

[0028] Figure 11 This is a diagram showing the supply state of inert gas during the unloaded voyage of the ship according to the second embodiment of the present invention.

[0029] Figure 12 This is a diagram showing the discharge state of inert gas during the loading of the ship according to the second embodiment of the present invention.

[0030] Figure 13 This is a diagram showing the discharge state of inert gas in the ship according to the second embodiment of the present invention.

[0031] Figure 14 This is a diagram showing the structure of the inert gas supply system according to the third embodiment of the present invention.

[0032] Figure 15 This is a diagram showing the supply state of inert gas during the voyage of the ship according to the third embodiment of the present invention.

[0033] Figure 16 This is a diagram showing the supply state of inert gas during the unloading of the ship according to the third embodiment of the present invention.

[0034] Figure 17 This is a diagram showing the supply state of inert gas during the unloaded voyage of the ship according to the third embodiment of the present invention.

[0035] Figure 18 This is a diagram showing the discharge state of inert gas during the loading of the ship according to the third embodiment of the present invention.

[0036] Figure 19It is another diagram showing the discharge state of inert gas in the ship according to the third embodiment of the present invention. Detailed Embodiment

[0037] Hereinafter, with reference to Figures 1 to 19 , embodiments of the inert gas supply system, ship, and inert gas supply method of the present invention will be described.

[0038] <First Embodiment>

[0039] (Overall Structure of Ship)

[0040] As Figure 1 shown, the ship 1 of the embodiment of the present invention includes at least a hull 2, a superstructure 4, a combustion device 9, a storage tank 10, and an inert gas supply system 20A. In addition, taking a ship that can navigate by a main engine or the like as an example, the ship 1 of this embodiment will be described. The ship type of the ship 1 is not limited to a specific ship type. As the ship type of the ship 1, a liquid carrier such as an oil tanker for transporting crude oil or liquid petroleum refined products refined from crude oil can be exemplified. As the petroleum refined products, gasoline, kerosene, naphtha, methanol, etc. can be exemplified.

[0041] The hull 2 has a pair of side plates 5A, 5B that form its outer shell and a bottom 6. The side plates 5A, 5B have a pair of outer side plates that respectively form the left and right side plates. The bottom 6 has a bottom outer plate that connects these side plates 5A, 5B.

[0042] The hull 2 further includes an upper deck 7 which is an all-through deck arranged on the topmost layer. The superstructure 4 is formed on this upper deck 7. A living area and the like are provided inside the superstructure 4.

[0043] In the ship 1 of this embodiment, for example, a cargo loading area (cargo hold) 8 is formed on the bow 2a side in the fore-and-aft direction FA more forward than the superstructure 4. The storage tank 10 is accommodated in the cargo loading area 8 of this embodiment.

[0044] The combustion device 9 is a device that generates heat energy by burning fuel, and it is provided inside the above-mentioned hull 2. As the combustion device 9, an internal combustion engine used in a main engine for propelling the ship 1, an internal combustion engine used in a power generation device for supplying power to the ship, a boiler that generates steam as a working fluid, etc. can be exemplified.

[0045] (Structure of Storage Tank Equipment)

[0046] The storage tanks 10 are arranged in a plurality of rows in the cargo loading area 8. In the present embodiment, an example is given in which five storage tanks 10A to 10E are arranged at intervals in the bow and stern direction FA. The storage tanks 10 contain liquid L such as crude oil or petroleum refined products refined from crude oil that are liquid at room temperature. In addition, the number and arrangement of the storage tanks 10 arranged in the cargo loading area 8 are not limited to the above-mentioned number and arrangement. Furthermore, the shape of the storage tanks 10 is not limited to Figure 1 The shapes shown.

[0047] (Structure of inert gas supply system)

[0048] Figure 2 It is a diagram showing the configuration of an inert gas supply system according to a first embodiment of the present invention.

[0049] like Figure 2 As shown, the ship 1 includes a liquid piping unit 15 for loading and unloading the liquid L into and from each of the plurality of tanks 10 . The liquid piping unit 15 includes a connecting pipe 16 and a plurality of branch pipes 17 .

[0050] The connection pipe 16 is connected to a fuel bunker station (not shown) or the like, and can be connected to a storage facility 200 (see FIG. 1 ) outside the ship 1 via the fuel bunker station. Figure 5 )、Supply facilities 300 (reference Figure 7 ) and other off-board equipment. An on-off valve 16v is provided in the middle of the connecting pipe 16 to intermittently transport the liquid L through the connecting pipe 16. In the present embodiment, an example is given of a case where only one on-off valve 16v is provided on the side closer to the fuel storage station (not shown) than the branch pipe 17, but the number and arrangement of the on-off valves 16v are not limited to the above structure as long as the liquid L can be transported intermittently through the connecting pipe 16.

[0051] A plurality of branch pipes 17 are provided in a manner that connects the inside of each storage tank 10 with the connecting pipe 16. The plurality of branch pipes 17 are respectively provided with a valve for intermittently circulating the liquid L through the branch pipes 17 and a loading and unloading pump for conveying the liquid L to the outside of the storage tank 10 through the branch pipes 17 (all not shown). In addition, the liquid piping section 15 is not limited to the above-mentioned structure. For example, a liquid piping section 15 for loading the liquid L in each of the plurality of storage tanks 10 and a liquid piping section 15 for unloading the liquid L may be provided respectively.

[0052] (Structure of inert gas supply system)

[0053] The inert gas supply system 20A can supply inert gas G to the storage tank 10. The inert gas supply system 20A includes a carbon dioxide recovery section 21, an inert gas supply section 22A, and a carbon dioxide discharge section 50.

[0054] The carbon dioxide recovery section 21 recovers carbon dioxide from the exhaust gas of the combustion device 9. The inert gas supply system 20A exemplified in the present embodiment is provided on the upper deck 7 of the hull 2, but the arrangement of the inert gas supply system 20A is not limited to the upper deck 7.

[0055] Here, as a method of recovering carbon dioxide contained in the exhaust gas by the carbon dioxide recovery section 21, a method of recovering carbon dioxide after absorbing the carbon dioxide contained in the exhaust gas by an absorption liquid through a chemical absorption method can be used. As the absorption liquid for absorbing this carbon dioxide by the chemical absorption method, MEA (monoethanolamine) can be exemplified. When MEA is heated, the absorbed carbon dioxide is separated in a gaseous state. Therefore, in the carbon dioxide recovery section 21, the separated carbon dioxide is recovered. In addition, although the case where the carbon dioxide recovery section 21 uses a chemical absorption method based on MEA to recover carbon dioxide has been described, as long as the carbon dioxide contained in the exhaust gas can be recovered, the structure is not limited to the above.

[0056] The inert gas supply section 22A supplies the carbon dioxide recovered by the carbon dioxide recovery section 21 to the storage tank 10 as inert gas G. In the first embodiment of the present invention, as the inert gas supply section 22A, a carbon dioxide supply pipe 23A and a piping section 24A are provided.

[0057] One end of the carbon dioxide supply pipe 23A is connected to the carbon dioxide recovery section 21. The other end of the carbon dioxide supply pipe 23A is connected to the piping section 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 the carbon dioxide from the carbon dioxide recovery section 21 through the carbon dioxide supply pipe 23A.

[0058] The piping section 24A has a connecting pipe 26A and a plurality of branch pipes 27.

[0059] The connecting pipe 26A is connected to the other end of the carbon dioxide supply pipe 23A. A plurality of branch pipes 27 are branched and connected to the connecting pipe 26A. The plurality of branch pipes 27 respectively communicate the connecting pipe 26A with the gas in each storage tank 10. Valves (not shown) for intermittently flowing the carbon dioxide through the branch pipes 27 are provided on the plurality of branch pipes 27 respectively.

[0060] The inert gas supply unit 22A can supply the carbon dioxide recovered by the carbon dioxide recovery unit 21 as an inert gas G to each of the plurality of storage tanks 10 by opening the respective valves (not shown) of the plurality of branch pipes 27 together with the opening of the on-off valve 231. At this time, the carbon dioxide is supplied to the storage tank 10 only through the branch pipe 27 of the opened valve among the plurality of branch pipes 27, and is not supplied to the storage tank 10 through the branch pipe 27 of the closed valve. That is, by separately opening and closing the valves of the plurality of branch pipes 27, it is possible to separately select the storage tank 10 to which carbon dioxide is supplied and the storage tank 10 to which carbon dioxide is not supplied from the plurality of storage tanks 10.

[0061] The carbon dioxide discharge unit 50 discharges the gas in the gas phase in the storage tank 10 to the outside of the ship 1. The carbon dioxide discharge unit 50 of the present embodiment includes a discharge pipe 51 and an on-off valve 52. One end of the discharge pipe 51 is connected to the connection pipe 26A. The other end of the discharge pipe 51 is connected to a fuel storage station (not shown) or the like, and can be connected to an external storage facility 200 (reference Figure 5 ), supply facility 300 (reference Figure 7 ) and other off-ship equipment. The on-off valve 52 intermittently discharges the gas passing through the discharge pipe 51.

[0062] The gas in the gas phase in the storage tank 10 becomes a state in which it can be discharged to the outside of the ship 1 via the carbon dioxide discharge unit 50, for example, by opening the valve (not shown) of the branch pipe 27 together with the opening of the on-off valve 52. At this time, it becomes a state in which the gas in the storage tank 10 can be discharged only through the branch pipe 27 of the opened valve among the plurality of branch pipes 27. That is, by separately opening and closing the valves of the plurality of branch pipes 27, it is possible to separately select the storage tank 10 that discharges the gas in the gas phase and the storage tank 10 that does not discharge the gas in the gas phase from the plurality of storage tanks 10.

[0063] (Steps of the inert gas supply method)

[0064] Figure 3 is a flowchart showing the steps of the inert gas supply method according to the embodiment of the present invention.

[0065] As Figure 3 shown, the inert gas supply method S10 according to the embodiment of the present invention includes: a step S11 of recovering carbon dioxide; and a step S12 of supplying carbon dioxide to the storage tank 10.

[0066] In the step S11 of recovering carbon dioxide, the carbon dioxide recovery unit 21 recovers the carbon dioxide contained in the exhaust gas from the combustion device 9 that burns fuel.

[0067] In the process S12 of supplying carbon dioxide to the storage tank 10, the recovered carbon dioxide is supplied to the storage tank 10 as the inert gas G. For this purpose, in the inert gas supply unit 22A, the respective valves (not shown) of the plurality of branch pipes 27 are opened together with the opening of the on-off valve 231. As a result, the carbon dioxide recovered by the carbon dioxide recovery unit 21 is supplied as the inert gas G from the carbon dioxide recovery unit 21 into the respective gas phases of the plurality of storage tanks 10.

[0068] (Supply of inert gas during navigation)

[0069] Figure 4 It is a diagram showing the supply state of inert gas during the navigation of the ship.

[0070] As Figure 4 shown, in the state where the liquid L is loaded in the storage tank 10, when the ship 1 sails, the carbon dioxide recovered by the carbon dioxide recovery unit 21 is filled as the inert gas G into the respective gas phases of the plurality of storage tanks 10 through the inert gas supply unit 22A.

[0071] During the navigation of the ship 1, due to the temperature difference between day and night, the radiant heat generated by the sunlight during the day, etc., the temperature inside the storage tank 10 changes. Along with the change in the temperature inside the storage tank 10, the pressure inside the storage tank 10 also changes. Correspondingly, the inert gas supply unit 22A supplies (in other words, replenishes) carbon dioxide into the storage tank 10 by the above-mentioned inert gas supply method S10, and keeps the pressure inside the storage tank 10 above a specified value to prevent the air outside the storage tank 10 from entering the storage tank 10 due to the pressure inside the storage tank 10 being lower than the pressure outside the storage tank 10.

[0072] (Supply of inert gas during unloading)

[0073] Figure 5 It is a diagram showing the supply state of inert gas during the unloading of the ship.

[0074] As Figure 5 shown, when the ship 1 unloads the liquid L in the storage tank 10 to the storage facility 200 such as a combined facility set on land that is the receiving destination of the liquid L such as crude oil or petroleum products, the connecting pipe 16 of the liquid pipe section 15 is connected to the storage facility 200 via a bunkering station or the like.

[0075] In this state, the on-off valve 16v of the connecting pipe 16 in the plurality of storage tanks 10 and the storage tank 10 where unloading is performed (in Figure 4In the example, the valve (not shown) of the branch piping 17 connected to the storage tank 10D) operates the loading and unloading pump of the branch piping 17. As a result, the liquid L in the storage tank 10 is unloaded into the storage facility 200 through the liquid piping section 15. In this way, the unloading of multiple storage tanks 10 is carried out in sequence.

[0076] In this way, when unloading the liquid L in the storage tank 10 into the storage facility 200, in the storage tank 10 where the unloading of the liquid L is in progress (in Figure 4 the example, it is the storage tank 10D)), the liquid level in the storage tank 10 gradually drops. According to this drop in the liquid level, the inert gas supply section 22A supplies carbon dioxide into the storage tank 10 through the above-mentioned inert gas supply method S10. That is, the inert gas supply section 22A supplies carbon dioxide as the inert gas G into the gas phase of the storage tank 10 where the unloading of the liquid L is in progress (in Figure 4 the example, it is the storage tank 10D)). For this purpose, the valve (not shown) of the branch piping 27 of the storage tank 10 where the unloading is in progress (in Figure 4 the example, it is the storage tank 10D)) is opened together with the opening and closing valve 231. As a result, the storage amount of the inert gas G in the storage tank 10 can be increased according to the drop in the liquid level in the storage tank 10 where the unloading is in progress, so that the pressure drop in the storage tank 10 can be suppressed.

[0077] (Supply of inert gas during ballast voyage)

[0078] Figure 6 is a diagram showing the supply state of inert gas during the ballast voyage of the ship.

[0079] As Figure 6 shown, in the ballast state where the unloading of the liquid L in the storage tank 10 is completed, carbon dioxide is filled as the inert gas G in the storage tank 10. When the ship 1 sails in the ballast state towards the supply facility 300 (refer to Figure 7 ) that is the supply source of the liquid L such as crude oil or petroleum products in order to reload the liquid L into the storage tank 10, the state where carbon dioxide is filled as the inert gas G in the storage tank 10 is maintained.

[0080] In this case, the inert gas supply section 22A also supplies carbon dioxide into the storage tank 10 through the above-mentioned inert gas supply method S10 and maintains it above a specified value so that during the voyage of the ship 1, the pressure inside the storage tank 10 does not become lower than the pressure outside the storage tank 10 due to changes in the temperature inside the storage tank 10 caused by the temperature difference between day and night, radiant heat generated by sunlight during the day, etc.

[0081] (Supply of inert gas during loading)

[0082] Figure 7 is a diagram showing the discharge state of inert gas during the loading of the ship. AsFigure 7 As shown, when the ship 1 loads the liquid L from the supply facility 300 which is a supply source of a liquid L such as crude oil or petroleum refined products into the storage tank 10, the connecting pipe 16 of the liquid pipe section 15 is connected via a fuel storage station (not shown) or the like to the external supply facility 300 of the ship 1.

[0083] 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 operated. Thereby, the liquid L is loaded into the storage tank 10 from the supply facility 300 through the liquid pipe section 15.

[0084] Thus, when loading the liquid L from the supply facility 300 into the storage tank 10, the other end of the discharge pipe 51 is connected to the supply facility 300 via a fuel storage station (not shown). Moreover, the valve (not shown) of the branch pipe 27 connected to the storage tank 10 where the liquid L is being loaded is opened together with the opening of the on-off valve 52 of the discharge pipe 51. As the storage amount of the liquid L in the storage tank 10 increases, the liquid level in the storage tank 10 gradually rises, and the gas in the gas phase in the storage tank 10, that is, the inert gas G filled in the storage tank 10, is extruded out of the storage tank 10. The extruded carbon dioxide is discharged to the supply facility 300 through the carbon dioxide discharge section 50.

[0085] Here, the supply facility 300 can send the gas in the gas phase in the storage tank 10 discharged from the ship 1 (in other words, the inert gas G, carbon dioxide) as the inert gas G into a storage tank (not shown) for storing the liquid L in the supply facility 300. And when the supply facility 300 is connected to the oil field 301 for extracting crude oil, the gas in the gas phase in the storage tank 10 discharged from the ship 1 can also be sent into the oil field 301.

[0086] (Function and effect)

[0087] In the inert gas supply system 20A, the ship 1 and the inert gas supply method S10 of the above first embodiment, the carbon dioxide contained in the exhaust gas from the combustion device 9 that burns fuel is recovered, and the recovered carbon dioxide is supplied as the inert gas G to the storage tank 10. Thus, by using the carbon dioxide contained in the exhaust gas as the inert gas G, the carbon dioxide can be effectively utilized, and there is no need to use other inert gases as the inert gas G. Therefore, the need to drive engines, boilers, fans, etc. for supplying the inert gas G into the storage tank 10 is suppressed. Therefore, the energy consumption based on the inert gas supply system 20A can be suppressed, the energy consumption in the ship 1 where the available energy is limited can be suppressed, and thus the emission of greenhouse gases can be suppressed.

[0088] Further, in the above-described first embodiment, carbon dioxide is supplied into the storage tank 10 so that the pressure inside the storage tank 10 does not become lower than the pressure outside the storage tank 10 due to changes in the external air temperature. Thereby, the gas phase inside the storage tank 10 can be filled with carbon dioxide as the inert gas G, and a decrease in the gas phase pressure inside the storage tank 10 can be suppressed.

[0089] Further, in the above-described first embodiment, when loading crude oil or petroleum products into the storage tank 10 from the supply facility 300, the carbon dioxide stored in the storage tank 10 is sent into the supply facility 300 through the carbon dioxide discharge section 50. Thereby, it is possible to recover the carbon dioxide contained in the exhaust gas of the combustion device 9 recovered during the navigation of the ship 1 through the supply facility 300 without releasing it into the atmosphere. In the supply facility 300, the recovered carbon dioxide can be filled as the inert gas G into a storage tank or the like of the supply facility 300, or filled into the oil field 301, so that the amount of inert gas and carbon dioxide used in the supply facility 300 can be reduced.

[0090] <Second Embodiment>

[0091] Next, a second embodiment of the inert gas supply system, ship, and inert gas supply method according to the present invention will be described. In the second embodiment described below, since only the structure of the inert gas supply system is different from that of the first embodiment, the same reference numerals are used for Figure 1 、 Figure 3 parts identical to those of the first embodiment for description, and repeated descriptions are omitted.

[0092] Figure 8 is a diagram showing the structure of the inert gas supply system according to the second embodiment of the present invention.

[0093] As Figure 8 shown, the inert gas supply system 20B provided in the ship 1 of this embodiment can supply the inert gas G to the storage tank 10. The inert gas supply system 20B includes at least a carbon dioxide recovery section 21, an inert gas supply section 22B, and a carbon dioxide discharge section 50.

[0094] The inert gas supply section 22B supplies the carbon dioxide recovered by the carbon dioxide recovery section 21 to the storage tank 10 as the inert gas G. In the second embodiment of the present invention, as the inert gas supply section 22B, a carbon dioxide supply pipe 23B, a carbon dioxide storage section 30B, and a piping section 24B are provided.

[0095] The carbon dioxide storage section 30B stores the carbon dioxide recovered by the carbon dioxide recovery section 21. The carbon dioxide storage section 30B of the second embodiment of the present invention includes a compressor 31 and a gaseous carbon dioxide storage tank 32.

[0096] 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 by the carbon dioxide recovery unit 21. The carbon dioxide compressed by the compressor 31 is transported to the gaseous carbon dioxide storage tank 32 through the connecting pipe 37.

[0097] 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 a carbon dioxide supply pipe 23B. A switching valve 232 is provided in the middle of the carbon dioxide supply pipe 23B. The switching valve 232 intermittently supplies the carbon dioxide from the gaseous carbon dioxide storage tank 32 to the plurality of storage tanks 10 through the carbon dioxide supply pipe 23B.

[0098] 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 from the connecting pipe 26B.

[0099] The inert gas supply section 22B can supply the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 to each storage tank 10 as an inert gas G by opening the valves (not shown) of the branch pipes 27 respectively connected to the plurality of storage tanks 10 together with the opening of the switching valve 232.

[0100] The carbon dioxide discharge section 50 includes a discharge pipe 51 and a switching valve 52. One end of the discharge pipe 51 is connected to the connecting pipe 26B. The other end of the discharge pipe 51 can be connected to external storage facilities 200 (refer to Figure 10 ), supply facilities 300 (refer to Figure 12 ) and other off - ship equipment of the ship 1 via a fuel storage station (not shown). A switching valve 52 is provided in the middle of the discharge pipe 51. The switching valve 52 intermittently discharges the carbon dioxide through the discharge pipe 51.

[0101] (Steps of the inert gas supply method)

[0102] As Figure 3 shown, the inert gas supply method S20 according to the embodiment of the present invention includes: a step S21 of recovering carbon dioxide; and a step S22 of supplying carbon dioxide to the storage tank 10.

[0103] In the step S21 of recovering carbon dioxide, the carbon dioxide contained in the exhaust gas of the combustion device 9 is recovered by the carbon dioxide recovery unit 21. In the step S21 of recovering carbon dioxide, 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.

[0104] In the process S22 of supplying carbon dioxide to the storage tank 10, the recovered carbon dioxide is supplied to the storage tank 10 as the inert gas G. For this purpose, in the inert gas supply unit 22B, the respective valves (not shown) of the plurality of branch pipes 27 are opened together with the opening of the on-off valve 232. As a result, the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 is supplied as the inert gas G from the carbon dioxide recovery unit 21 to the respective gas phases of the plurality of storage tanks 10.

[0105] (Supply of inert gas during navigation)

[0106] Figure 9 is a diagram showing the supply state of the inert gas during the navigation of the ship. As Figure 9 shown, in the state where the liquid L is loaded in the storage tank 10, when the ship 1 is navigating, through the inert gas supply unit 22B, the carbon dioxide recovered by the carbon dioxide recovery unit 21 is filled as the inert gas G into the respective gas phases of the plurality of storage tanks 10.

[0107] Moreover, during the navigation of the ship 1, the process S21 of the above-described inert gas supply method S20 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.

[0108] During the navigation of the ship 1, when the pressure inside the storage tank 10 is lower than the pressure outside the storage tank 10 due to a change in the external air temperature, the inert gas supply unit 22B executes the process S22 of the above-described inert gas supply method S20, and supplies the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 into the storage tank 10.

[0109] (Supply of inert gas during unloading)

[0110] Figure 10 is a diagram showing the supply state of the inert gas during the unloading of the ship.

[0111] As Figure 10 shown, when the ship 1 unloads the liquid L in the storage tank 10 to the storage facility 200 provided on land, the connecting pipe 16 of the liquid pipe section 15 is connected to the storage facility 200.

[0112] 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 loading and unloading pump of the branch pipe 17 is operated. As a result, the liquid L in the storage tank 10 is unloaded to the storage facility 200 through the liquid pipe section 15.

[0113] Thus, when unloading the liquid L in the storage tank 10 into the storage facility 200, the inert gas supply unit 22B performs the process S22 of the above-described inert gas supply method S20 on the storage tank 10 where the liquid L is being unloaded, and supplies the carbon dioxide stored in the gas carbon dioxide storage tank 32 as the inert gas G. As a result, as the liquid volume of the liquid L in the storage tank 10 decreases, the storage amount of the inert gas G in the storage tank 10 can be increased to maintain the pressure in the storage tank 10.

[0114] (Supply of inert gas during ballast voyage)

[0115] Figure 11 FIG. is a diagram showing the supply state of inert gas during ballast voyage of a ship.

[0116] As Figure 11 shown, in the ballast state where the unloading of the liquid L in the storage tank 10 is completed, carbon dioxide is filled as the inert gas G in the storage tank 10. When the ship 1 sails in the ballast state toward the supply facility 300 to reload the liquid L into the storage tank 10, the state where carbon dioxide is filled as the inert gas G in the storage tank 10 is maintained.

[0117] In this case, during the voyage of the ship 1, when the pressure in the storage tank 10 is lower than the pressure outside the storage tank 10 due to the change in the temperature in the storage tank 10, the inert gas supply unit 22B also performs the process S22 and supplies the carbon dioxide stored in the gas carbon dioxide storage tank 32 into the storage tank 10.

[0118] (Supply of inert gas during loading)

[0119] Figure 12 FIG. is a diagram showing the discharge state of inert gas during loading of a ship.

[0120] As Figure 12 shown, when loading the liquid L from the supply facility 300 into the storage tank 10, the other end of the discharge pipe 51 is connected to the supply facility 300 via a fuel storage station (not shown). Further, in the storage tank 10 where the liquid L is being loaded into the storage tank 10 while opening the on-off valve 52 of the discharge pipe 51 (in the example of Figure 4 is the storage tank 10D), the valve (not shown) of the branch pipe 27 is opened. Then, as the storage amount of the liquid L in the storage tank 10 increases, the gas in the gas phase in the storage tank 10, that is, the inert gas G filled in the storage tank 10 is extruded out of the storage tank 10. The extruded carbon dioxide is discharged to the supply facility 300 through the carbon dioxide discharge unit 50.

[0121] Figure 13 FIG. is another diagram showing the discharge state of inert gas in a ship.

[0122] As Figure 13 shown, the valve (not shown) of the branch pipe 27 can also be closed before and after loading the liquid L from the supply facility 300 into the storage tank 10, and the on-off valve 232 can be opened. Thus, the carbon dioxide stored in the carbon dioxide storage tank 32 is discharged to the supply facility 300 through the carbon dioxide discharge unit 50.

[0123] Here, the supply facility 300 can send the gas in the gas phase in the storage tank 10 discharged from the ship 1 (in other words, the inert gas G, carbon dioxide) as the inert gas G to the storage tank (not shown) for storing the liquid L in the supply facility 300. And when the supply facility 300 is connected to the oil field 301 where crude oil is produced, the carbon dioxide discharged from the ship 1 can also be sent to the oil field 301.

[0124] (Function and effect)

[0125] In the inert gas supply system 20B, the ship 1, and the inert gas supply method S20 of the second embodiment described above, similarly to the first embodiment, the energy consumption based on the inert gas supply system 20B can be suppressed, and thus the emission of greenhouse gases can be suppressed.

[0126] Moreover, in the second embodiment described above, there is provided a carbon dioxide storage unit 30B for storing the carbon dioxide recovered by the carbon dioxide recovery unit 21. Thus, the inert gas supply unit 22B can supply the carbon dioxide stored in the carbon dioxide storage unit 30B as the inert gas G to the storage tank 10. Thus, the carbon dioxide contained in the exhaust gas from the combustion device 9 can be stored in the carbon dioxide storage unit 30B, and regardless of the operating state of the combustion device 9, carbon dioxide can be supplied from the carbon dioxide storage unit 30B to the storage tank 10 at an appropriate time as needed. Thus, the carbon dioxide contained in the exhaust gas can be recovered, and the recovered carbon dioxide can be effectively utilized.

[0127] Furthermore, in the second embodiment described above, the carbon dioxide compressed by the compressor 31 is stored in the gas carbon dioxide storage tank 32 in a gaseous state. Thus, the carbon dioxide contained in the exhaust gas can be recovered and efficiently stored. Also, carbon dioxide can be sent from the gas carbon dioxide storage tank 32 to the storage tank 10 at an appropriate time. At this time, since the carbon dioxide in the gas carbon dioxide storage tank 32 is in a gaseous state, compared with the case where carbon dioxide is stored in a liquefied state, an amount of carbon dioxide that does not need to be gasified can be sent to the storage tank 10 more quickly.

[0128] <Third Embodiment>

[0129] Next, a third embodiment of the inert gas supply system, ship, and inert gas supply method according to the present invention will be described. In the third embodiment described below, since only the structure of the inert gas supply system is different from that of the first embodiment, the same reference numerals are used for the parts that are the same as those in the first embodiment, and duplicate descriptions are omitted. Figure 1 , Figure 3 The parts that are the same as those in the first embodiment are denoted by the same reference numerals and will not be described again.

[0130] Figure 14 FIG. is a diagram showing the structure of the inert gas supply system according to the third embodiment of the present invention.

[0131] As Figure 14 shown, the inert gas supply system 20C provided in the ship 1 of this embodiment can supply inert gas G to the storage tank 10. The inert gas supply system 20C includes at least a carbon dioxide recovery unit 21, an inert gas supply unit 22C, and a carbon dioxide discharge unit 50.

[0132] The inert gas supply unit 22C supplies the carbon dioxide recovered by the carbon dioxide recovery unit 21 to the storage tank 10 as inert gas G. The inert gas supply unit 22C of the third embodiment of the present invention includes a carbon dioxide storage unit 30C, two carbon dioxide supply pipes 23B, 23C, and a piping unit 24C.

[0133] The carbon dioxide storage unit 30C stores the carbon dioxide recovered by the carbon dioxide recovery unit 21. In the third embodiment of the present invention, the carbon dioxide storage unit 30C includes a compressor 31, a gaseous carbon dioxide storage tank 32, a liquefaction unit 33, and a liquid carbon dioxide storage tank 34.

[0134] The compressor 31 is connected to the carbon dioxide recovery unit 21 via a connection pipe 35. The compressor 31 compresses the carbon dioxide recovered by the carbon dioxide recovery unit 21. A part of the carbon dioxide compressed by the compressor 31 is transported to the gaseous carbon dioxide storage tank 32 through a connection pipe 37. The remaining part of the carbon dioxide compressed by the compressor 31 is transported to the liquefaction unit 33 through a connection pipe 38. In addition, the supply destination of the carbon dioxide discharged from the compressor 31 can also be selected from the gaseous carbon dioxide storage tank 32 and the liquefaction unit 33 through a plurality of valves (not shown), for example.

[0135] 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 unit 24C via a 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 the carbon dioxide from the gaseous carbon dioxide storage tank 32 to the plurality of storage tanks 10 through the carbon dioxide supply pipe 23B.

[0136] The liquefying unit 33 liquefies the carbon dioxide compressed by the compressor 31. As the liquefying unit 33, a refrigerator can be exemplified. The liquefying unit 33 transports the liquefied carbon dioxide to the liquid carbon dioxide storage tank 34 through the connecting pipe 39.

[0137] The liquid carbon dioxide storage tank 34 stores the carbon dioxide liquefied by the liquefying unit 33 in a liquid state. The liquid carbon dioxide storage tank 34 is connected to the piping unit 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 the carbon dioxide from the liquid carbon dioxide storage tank 34 to the plurality of storage tanks 10 through the carbon dioxide supply pipe 23C. A gasifying unit (not shown) is provided in the middle of the carbon dioxide supply pipe 23C. The gasifying unit gasifies the liquefied carbon dioxide sent out from the liquid carbon dioxide storage tank 34. As the gasifying unit, a heat exchanger can be exemplified, and as the heat medium of the gasifying unit, an antifreeze heated by steam or the like can be exemplified. Thus, the carbon dioxide gasified via the gasifying unit is supplied to each of the storage tanks 10.

[0138] The piping unit 24C has 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 branch from the connecting pipe 26C respectively.

[0139] The inert gas supply unit 22C can supply the carbon dioxide stored in the liquid carbon dioxide storage tank 34 as an inert gas G to each of the plurality of storage tanks 10 after gasifying it by opening the valve (not shown) of the branch pipe 27 together with opening the on-off valve 233. And, the inert gas supply unit 22C is the same as the inert gas supply unit 22B in the second embodiment, and can supply the carbon dioxide stored in the gas carbon dioxide storage tank 32 as an inert gas G to each of the plurality of storage tanks 10 by opening the respective valves (not shown) of the plurality of branch pipes 27 together with opening the on-off valve 232.

[0140] (Steps of the inert gas supply method)

[0141] As Figure 3 shown, the inert gas supply method S30 according to the embodiment of the present invention includes: a step S31 of recovering carbon dioxide; and a step S32 of supplying carbon dioxide to the storage tank 10.

[0142] In the carbon dioxide recovery process S31, the carbon dioxide contained in the exhaust gas of the combustion device 9 is recovered by the carbon dioxide recovery unit 21. In the carbon dioxide recovery process S31, after the carbon dioxide recovered by the carbon dioxide recovery unit 21 is compressed by the compressor 31, a part of it is stored in the gaseous carbon dioxide storage tank 32. In the carbon dioxide recovery process S31, after the carbon dioxide recovered by the carbon dioxide recovery unit 21 is compressed by the compressor 31, the remaining part is liquefied by the liquefaction unit 33 and stored in the liquid carbon dioxide storage tank 34.

[0143] In the process S32 of supplying carbon dioxide to the storage tank 10, the recovered carbon dioxide is supplied as an inert gas G to the storage tank 10. For this purpose, in the inert gas supply unit 22C, the respective valves (not shown) of the plurality of branch pipes 27 are opened together with the opening of the on-off valve 233. Thereby, after the carbon dioxide stored in the liquid carbon dioxide storage tank 34 is gasified, it is supplied as an inert gas G from the carbon dioxide recovery unit 21 to the gas phases of the plurality of storage tanks 10. And, in the inert gas supply unit 22C, the respective valves (not shown) of the plurality of branch pipes 27 are opened together with the opening of the on-off valve 232. Thereby, the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 can also be supplied as an inert gas G to the gas phases of the plurality of storage tanks 10.

[0144] (Supply of inert gas during navigation)

[0145] Figure 15 It is a diagram showing the supply state of inert gas during the navigation of the ship.

[0146] As Figure 15 shown, in the state where the liquid L is loaded in the storage tank 10, when the ship 1 sails, through the inert gas supply unit 22C, the carbon dioxide recovered by the carbon dioxide recovery unit 21 is filled as an inert gas G into the gas phases of the plurality of storage tanks 10.

[0147] And, during the navigation of the ship 1, the process S31 of the above-mentioned inert gas supply method S30 is executed, and the carbon dioxide recovered from the exhaust gas of the combustion device 9 is respectively stored in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34.

[0148] During the navigation of the ship 1, when the pressure inside the storage tank 10 is lower than the pressure outside the storage tank 10 due to the temperature difference between day and night, the radiant heat generated by the sunlight during the day, etc., through the process S32 of the above-mentioned inert gas supply method S30, the inert gas supply unit 22C supplies the carbon dioxide stored in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34 as an inert gas G into the storage tank 10.

[0149] (Supply of inert gas during unloading)

[0150] Figure 16 This is a diagram showing the supply state of inert gas during the unloading of a ship. As Figure 16 shown, when the ship 1 unloads the liquid L in the storage tank 10 to the storage facility 200 set on land, the connecting pipe 16 of the liquid pipe section 15 is connected to the storage facility 200 with the liquid.

[0151] 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 loading and unloading pump of the branch pipe 17 is operated. As a result, the liquid L in the storage tank 10 is unloaded to the storage facility 200 through the liquid pipe section 15.

[0152] Thus, when the liquid L in the storage tank 10 is unloaded to the storage facility 200, the inert gas supply unit 22C performs the process S32 of the above-described inert gas supply method S30 on the storage tank 10 where the liquid L is being unloaded. As a result, the carbon dioxide stored in the gas carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34 is supplied to the storage tank 10 being unloaded (in the Figure 16 example, it is the storage tank 10D). Therefore, as the liquid volume of the liquid L in the storage tank 10 decreases (in other words, the liquid level drops), the storage amount of the inert gas G in the storage tank 10 can be increased to maintain the pressure in the storage tank 10.

[0153] (Supply of inert gas during ballast voyage)

[0154] Figure 17 This is a diagram showing the supply state of inert gas during the ballast voyage of a ship.

[0155] As Figure 17 shown, in the ballast state where the unloading of the liquid L in the storage tank 10 is completed, carbon dioxide is filled in the storage tank 10 as the inert gas G. When the ship 1 sails in the ballast state toward the supply facility 300 to reload the liquid L into the storage tank 10, the state where carbon dioxide is filled in the storage tank 10 as the inert gas G is maintained.

[0156] In this case, during the voyage of the ship 1, when the pressure in the storage tank 10 is lower than the pressure outside the storage tank 10 due to the temperature difference between day and night and the radiant heat generated by the sunlight during the day, etc., the inert gas supply unit 22C also performs the process S32 of the above-described inert gas supply method S30. As a result, the carbon dioxide stored in the liquid carbon dioxide storage tank 34 is supplied into the storage tank 10.

[0157] (Supply of inert gas during loading)

[0158] Figure 18This is a diagram showing the discharge state of inert gas during the loading of a ship.

[0159] As Figure 18 shown, when loading the liquid L from the supply facility 300 into the storage tank 10, the other end of the discharge pipe 51 is connected to the supply facility 300 via a fuel storage station (not shown). Moreover, in the storage tank 10 (in the case of Figure 18 as an example, storage tank 10D) where the liquid L is being loaded into the storage tank 10 while the on-off valve 52 of the discharge pipe 51 is opened, the valve (not shown) of the branch pipe 27 is opened. Then, as the storage amount of the liquid L in the storage tank 10 increases, the gas in the gas phase in the storage tank 10, that is, the inert gas G filled in the storage tank 10, is squeezed out of the storage tank 10. The discharged carbon dioxide is discharged to the supply facility 300 through the carbon dioxide discharge section 50.

[0160] Figure 19 This is another diagram showing the discharge state of inert gas in the ship.

[0161] As Figure 19 shown, the valve (not shown) of the branch pipe 27 can be closed before and after loading the liquid L from the supply facility 300 into the storage tank 10, and the on-off valve 232 and the on-off valve 233 can be opened. Thereby, 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.

[0162] Here, similar to the above-described respective embodiments, the supply facility 300 can also send the gas in the gas phase of the storage tank 10 discharged from the ship 1 (in other words, the inert gas G, carbon dioxide) as the inert gas G into a storage tank (not shown) for storing the liquid L in the supply facility 300. And when the supply facility 300 is connected to the oil field 301 for extracting crude oil, the carbon dioxide discharged from the ship 1 can also be sent into the oil field 301.

[0163] (Function and effect)

[0164] In the inert gas supply system 20C, the ship 1, and the inert gas supply method S30 of the above-described third embodiment, similar to the above-described first embodiment and second embodiment, it is possible to suppress the energy consumption based on the inert gas supply system 20C, and thus it is possible to suppress the emission of greenhouse gases.

[0165] Also, in the above-described third embodiment, a carbon dioxide storage unit 30C is provided for storing the carbon dioxide recovered by the carbon dioxide recovery unit 21. Thus, the inert gas supply unit 22C can supply the carbon dioxide stored in the carbon dioxide storage unit 30C to the storage tank 10 as the inert gas G. Therefore, the carbon dioxide contained in the exhaust gas of the combustion device 9 can be stored in the carbon dioxide storage unit 30C, and at an appropriate time as needed, carbon dioxide can be supplied from the carbon dioxide storage unit 30C to the storage tank 10 as the inert gas G. Therefore, the carbon dioxide contained in the exhaust gas can be recovered, and the recovered carbon dioxide can be effectively utilized.

[0166] Also, in the above-described third embodiment, since the carbon dioxide liquefied by the liquefaction unit 33 is stored in the liquid carbon dioxide storage tank 34 in a liquid state, more carbon dioxide can be stored without expanding the storage space compared to the case of storing it in a gaseous state. Therefore, more carbon dioxide can be stored in the limited space of the ship 1. In addition, carbon dioxide can be fed from the liquid carbon dioxide storage tank 34 to the storage tank 10 as the inert gas G at an appropriate time.

[0167] (Other embodiments)

[0168] As described above, the embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the specific structure is not limited to this embodiment, and also includes design changes and the like within the scope not departing from the gist of the present invention.

[0169] For example, in the above-described second and third embodiments, 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 it is not limited thereto. The carbon dioxide stored in the gaseous carbon dioxide storage tank 32 and the liquid carbon dioxide storage tank 34 can be discharged to a carbon dioxide recovery device provided in a harbor or the like. In addition, although the case where the supply facility 300 is provided on land has been described, the supply facility 300 can also be provided on other ships.

[0170] Also, in the above-described third embodiment, a structure not having the gaseous carbon dioxide storage tank 32 can also be adopted.

[0171] In addition, the structure of the first embodiment can also be combined in the above-described second and third embodiments. More specifically, a structure in which the carbon dioxide recovered by the carbon dioxide recovery unit 21 is directly fed into the storage tank 10 through the carbon dioxide supply pipe 23A as in the above-described first embodiment can be added to the structures of the second and third embodiments.

[0172] Further, in each of the above embodiments, the case where the carbon dioxide recovered by the ship 1 is supplied to the storage tank of the supply facility 300, the oil field 301, etc. in the supply facility 300 has been described, but it is not limited thereto. In the supply facility 300, the recovered carbon dioxide and materials obtained from crude oil can be used to generate products such as methane and methanol.

[0173] <Supplementary Note>

[0174] 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 as follows, for example.

[0175] (1) Regarding the inert gas supply systems 20A to 20C according to the first mode, they are provided on the ship 1 and can supply inert gas G to the storage tank 10 capable of storing crude oil or petroleum products. The inert gas supply systems 20A to 20C include: a carbon dioxide recovery unit 21 that recovers carbon dioxide contained in the exhaust gas from the 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 to the storage tank 10 as inert gas G.

[0176] Examples of the combustion device 9 include internal combustion engines and boilers.

[0177] Examples of petroleum products include gasoline, kerosene, naphtha, and methanol.

[0178] The inert gas supply systems 20A to 20C recover the carbon dioxide contained in the exhaust gas from the combustion device 9 that burns fuel and supply the recovered carbon dioxide to the storage tank 10 as inert gas G. In this way, by using the carbon dioxide contained in the exhaust gas as inert gas G, carbon dioxide can be effectively utilized, and there is no need to use other non-reactive gases as inert gas G. Therefore, the need to drive engines, boilers, fans, etc. to supply non-reactive gases used as inert gas G into the storage tank 10 is suppressed. Therefore, there is no need for energy such as fuel required to drive engines, boilers, fans, etc. to supply inert gas G to the storage tank 10. Therefore, in the ship 1 where the available energy is limited, energy consumption can be suppressed, and thus greenhouse gas emissions can be suppressed.

[0179] (2) The inert gas supply systems 20B and 20C according to the second mode are the inert gas supply systems 20B and 20C of (1), and further include: carbon dioxide storage units 30B and 30C that store the carbon dioxide recovered by the carbon dioxide recovery unit 21, and the inert gas supply units 22B and 22C supply the carbon dioxide stored in the carbon dioxide storage units 30B and 30C to the storage tank 10 as the inert gas G.

[0180] In this structure, by including the carbon dioxide storage units 30B and 30C that store 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 storage tank 10 as the inert gas G. Thus, the carbon dioxide contained in the exhaust gas from the combustion device 9 can be stored in the carbon dioxide storage units 30B and 30C, and at an appropriate time as needed, carbon dioxide can be supplied from the carbon dioxide storage units 30B and 30C to the storage tank 10. Thus, the carbon dioxide contained in the exhaust gas can be recovered, and the recovered carbon dioxide can be effectively utilized.

[0181] (3) The inert gas supply systems 20B and 20C according to the third mode are the inert gas supply systems 20B and 20C of (2), wherein the carbon dioxide storage units 30B and 30C include: a compressor 31 that compresses the carbon dioxide; and a gaseous carbon dioxide storage tank 32 that stores the carbon dioxide compressed by the compressor 31 in a gaseous state.

[0182] Thus, by storing the carbon dioxide compressed by the compressor 31 in a gaseous state in the gaseous carbon dioxide storage tank 32, the carbon dioxide contained in the exhaust gas can be recovered and efficiently stored. Moreover, carbon dioxide can be fed from the gaseous carbon dioxide storage tank 32 to the storage tank 10 at an appropriate time. At this time, since the carbon dioxide in the gaseous carbon dioxide storage tank 32 is in a gaseous state, carbon dioxide can be quickly fed into the storage tank 10 without gasification compared to the case of liquefying carbon dioxide.

[0183] (4) The inert gas supply system 20C according to the fourth mode is the inert gas supply system 20C of (2) or (3), and the carbon dioxide storage unit 30C includes: a liquefaction unit 33 that liquefies the carbon dioxide; and a liquid carbon dioxide storage tank 34 that stores the carbon dioxide liquefied by the liquefaction unit 33.

[0184] Thus, by storing the carbon dioxide liquefied by the liquefaction unit 33 in a liquid state in the liquid carbon dioxide storage tank 34, more carbon dioxide can be stored in a limited space. Moreover, carbon dioxide can be fed from the liquid carbon dioxide storage tank 34 to the storage tank 10 at an appropriate time.

[0185] (5) The inert gas supply systems 20B and 20C according to the fifth mode are any of the inert gas supply systems 20B and 20C in (2) to (4). When discharging the crude oil or petroleum product from the storage tank 10 to the outside of the storage tank 10, the inert gas supply units 22B and 22C supply the carbon dioxide stored in the carbon dioxide storage units 30B and 30C into the gas phase in the storage tank 10 according to the decrease in the liquid level of the liquid phase in the storage tank 10.

[0186] Thus, when discharging the crude oil or petroleum product from the storage tank 10 to the outside of the storage tank 10, according to the decrease in the liquid level of the liquid phase in the storage tank 10, the carbon dioxide stored in the carbon dioxide storage unit 30B is supplied into the gas phase in the storage tank 10. Thus, it is possible to maintain the state where the gas phase in the storage tank 10 is filled with carbon dioxide. And after discharging the crude oil or petroleum product to the outside of the storage tank 10, it is possible to make the whole inside the storage tank 10 filled with carbon dioxide.

[0187] (6) The inert gas supply systems 20A to 20C according to the sixth mode are any of the inert gas supply systems 20A to 20C in (1) to (5). When the pressure in the storage tank 10 is lower than the pressure outside the storage tank 10 due to the change in the external air temperature, the inert gas supply units 22A to 22C supply the carbon dioxide into the storage tank 10.

[0188] Thus, when the pressure in the storage tank 10 is lower than the pressure outside the storage tank 10 due to the change in the external air temperature, by supplying carbon dioxide into the storage tank 10, it is possible to fill the gas phase in the storage tank 10 with carbon dioxide and suppress the decrease in the gas phase pressure in the storage tank 10.

[0189] (7) The inert gas supply systems 20A to 20C according to the seventh mode are any of the inert gas supply systems 20A to 20C in (1) to (6). It further includes: a carbon dioxide discharge unit 50 that discharges the carbon dioxide stored in the storage tank 10 to the outside of the ship 1. When loading the crude oil or petroleum product from the supply facility 300 for the crude oil or petroleum product provided outside the ship 1 into the storage tank 10, the carbon dioxide stored in the storage tank 10 is sent into the supply facility 300 through the carbon dioxide discharge unit 50.

[0190] According to this structure, when loading crude oil or refined petroleum products from the supply facility 300 of crude oil or refined petroleum products into the storage tank 10, the carbon dioxide stored in the storage tank 10 is sent into the supply facility 300 through the carbon dioxide discharge section 50. Thereby, the release of carbon dioxide contained in the exhaust gas from the combustion device 9 recovered during the navigation of the ship 1 into the atmosphere is suppressed, and it can be recovered through the supply facility 300. In the supply facility 300, the recovered carbon dioxide can also be filled as the inert gas G into the supply facility 300 storing the crude oil or refined petroleum products loaded in the storage tank 10 of the ship 1, the oil field for extracting crude oil, etc. Thereby, the need for separately preparing an inert gas as the inert gas G is also suppressed on the supply facility 300 side.

[0191] (8) The ship 1 according to the eighth aspect includes a hull 2 and any one of the inert gas supply systems 20A to 20C in (1) to (7).

[0192] Thereby, the energy consumption in the ship 1 can be suppressed, and thus the emission of greenhouse gases can be suppressed.

[0193] (9) The inert gas supply methods S10, S20, S30 according to the ninth aspect are the inert gas supply methods S10, S20, S30 in any one of the inert gas supply systems 20A to 20C in (1) to (7), and include: a step S11 of recovering carbon dioxide contained in the exhaust gas from the combustion device 9 that burns fuel; and a step S12 of supplying the recovered carbon dioxide as the inert gas G to the storage tank 10.

[0194] Thereby, carbon dioxide contained in the exhaust gas from the combustion device 9 that burns fuel is recovered, and the recovered carbon dioxide is supplied as the inert gas G to the storage tank 10. Thereby, the energy consumption in the ship 1 can be suppressed, and thus the emission of greenhouse gases can be suppressed.

[0195] Industrial applicability

[0196] According to the inert gas supply system, ship, and inert gas supply method of the present invention, the emission of greenhouse gases can be suppressed.

[0197] Reference numerals

[0198] 1 - Ship, 2 - Hull, 2a - Bow, 4 - Superstructure, 5A, 5B - Side, 6 - Bottom, 7 - Upper deck, 8 - Cargo loading area, 9 - Combustion device, 10, 10A~10E - Storage tank, 15 - Liquid piping section, 16 - Connecting pipe, 16v - On-off valve, 17 - Branch pipe, 20A~20C - Inert gas supply system, 21 - Carbon dioxide recovery section, 22A~22C - Inert gas supply section, 23A~23C - Carbon dioxide supply pipe, 231~233 - On-off valve, 24A~24C - Piping section, 26A~26C - Connecting pipe, 27 - Branch pipe, 30B, 30C - Carbon dioxide storage section, 31 - Compressor, 32 - Gas carbon dioxide storage tank, 33 - Liquefaction section, 34 - Liquid carbon dioxide storage tank, 35, 37, 38, 39 - Connecting pipe, 50 - Carbon dioxide discharge section, 51 - Discharge pipe, 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 the storage tank.

Claims

1. An inert gas supply system is provided on a ship and is capable of supplying inert gas to a storage tank capable of storing crude oil or petroleum refined products. The inert gas supply system includes: A carbon dioxide recovery unit that recovers carbon dioxide contained in the 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 as inert gas to the storage tank.

2. The inert gas supply system according to claim 1, further comprising: A carbon dioxide storage unit that stores the carbon dioxide recovered by the carbon dioxide recovery unit, and the inert gas supply unit supplies the carbon dioxide stored in the carbon dioxide storage unit as inert gas to the storage tank.

3. The inert gas supply system according to claim 2, wherein, The carbon dioxide storage unit includes: a compressor that compresses the carbon dioxide; and a gaseous carbon dioxide storage tank that stores the carbon dioxide compressed by the compressor in a gaseous state.

4. The inert gas supply system according to claim 2 or 3, wherein, The carbon dioxide storage unit includes: a liquefaction unit that liquefies the carbon dioxide; and a liquid carbon dioxide storage tank that stores the carbon dioxide liquefied by the liquefaction unit.

5. The inert gas supply system according to claim 2, wherein, When discharging the crude oil or petroleum refined product from the storage tank to the outside of the storage tank, the inert gas supply unit supplies the carbon dioxide stored in the carbon dioxide storage unit into the gas phase in the storage tank according to the decrease in the liquid level of the liquid phase in the storage tank.

6. The inert gas supply system according to claim 1 or 2, wherein, When the pressure in the storage tank is lower than the pressure outside the storage tank due to changes in the external air temperature, the inert gas supply unit supplies the carbon dioxide into the storage tank.

7. The inert gas supply system according to claim 1 or 2, further comprising: A carbon dioxide discharge unit that discharges the carbon dioxide stored in the storage tank to the outside of the ship, and when loading the crude oil or petroleum refined products from a supply facility for the crude oil or petroleum refined products provided outside the ship into the storage tank, the carbon dioxide stored in the storage tank is sent into the supply facility through the carbon dioxide discharge unit.

8. A ship includes: A hull; A storage tank provided on the hull and capable of storing crude oil or petroleum refined products; and The inert gas supply system according to claim 1 or 2.

9. A method for supplying an inert gas, which is the method for supplying an inert gas in the inert gas supply system according to claim 1 or 2, the method for supplying an inert gas comprising: a process of recovering carbon dioxide contained in the exhaust gas from a combustion device that burns fuel; and a process of supplying the recovered carbon dioxide as an inert gas to the storage tank.

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