Method for pressure adjustment of a ship, of a tank in a ship

Abstract

A ship includes a hull, a tank provided in the hull and storing liquefied carbon dioxide, and a carbon dioxide injection portion provided in the hull and capable of injecting carbon dioxide gas having a temperature and a pressure higher than those of the carbon dioxide in the tank into the tank.

Description

Technical Field

[0001] This invention relates to a ship and a method for adjusting the pressure of a storage tank in a ship.

[0002] This application claims priority to Japanese Patent Application No. 2021-059785, filed on March 31, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] Patent document 1 discloses a structure for transporting dry ice that is released by spraying liquid carbon dioxide inside the ship's hold.

[0004] Furthermore, Patent Document 2 discloses a value of 15 kg / cm². 2 It transports carbon dioxide in the form of compressed carbon dioxide gas under the pressure of the storage tank and at normal temperature (e.g., 0–30°C).

[0005] Previous technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 5-180394

[0008] Patent Document 2: Japanese Patent Application Publication No. 2004-125039 Summary of the Invention

[0009] The technical problem to be solved by the invention

[0010] When liquefied carbon dioxide is stored in tanks located within a ship's hull, it may freeze and form dry ice for the following reasons: The pressure of the liquefied carbon dioxide inside the tank corresponds to the operating pressure of the tank. The triple point pressure (the pressure at which the gas, liquid, and solid phases of liquefied carbon dioxide coexist) is higher than the triple point pressure of liquefied natural gas (LNG) or liquefied petroleum gas (LPG). If the tank is depressurized during application, it may reach the triple point.

[0011] If the pressure of liquefied carbon dioxide falls below its triple point, flash evaporation may occur. Due to the latent heat of vaporization from this flash evaporation, the temperature of the remaining liquefied carbon dioxide decreases, potentially causing it to condense inside the tank and form dry ice. Therefore, the tank's application pressure (design pressure) should be set so that the pressure of the liquefied carbon dioxide does not fall below its triple point. However, if the tank's application pressure is set significantly higher than the triple point of liquefied carbon dioxide, the tank itself or the piping connected to it must be constructed with a pressure-resistant structure corresponding to the tank's application pressure (design pressure), leading to increased costs.

[0012] Furthermore, for example, when the liquefied carbon dioxide in the storage tank sways with the ship's movement, the dynamic pressure of the liquefied carbon dioxide increases accordingly with its flow rate, while its static pressure decreases. Due to this decrease in static pressure, the liquefied carbon dioxide may condense inside the tank to form dry ice.

[0013] Moreover, because dry ice is denser than liquefied carbon dioxide, it settles and accumulates at the bottom of the storage tank when it forms. Therefore, even after the pressure inside the tank is restored, the sublimation of dry ice may still take a long time.

[0014] This invention was made to solve the above-mentioned problems, and its purpose is to provide a ship capable of suppressing the formation of dry ice and smoothly carrying out the application of storage tanks, and a method for adjusting the pressure of storage tanks in ships.

[0015] means for solving technical problems

[0016] To address the aforementioned issues, the vessel of the present invention comprises a hull, a storage tank, and a carbon dioxide injection unit. The storage tank is disposed within the hull. The storage tank stores liquefied carbon dioxide. The carbon dioxide injection unit is disposed within the hull. The carbon dioxide injection unit is capable of injecting carbon dioxide gas with a temperature and pressure higher than that of the carbon dioxide in the storage tank into the storage tank.

[0017] The pressure adjustment method for a storage tank in a ship according to the present invention is as described above, comprising a step of acquiring information and a step of injecting carbon dioxide gas into the storage tank. In the step of acquiring the information, at least one of information relating to the pressure inside the storage tank and information relating to the sloshing of the liquefied carbon dioxide stored in the storage tank is acquired. In the step of injecting the carbon dioxide gas into the storage tank, the carbon dioxide gas is injected into the storage tank by the carbon dioxide injection unit according to the acquired information.

[0018] Invention Effects

[0019] The pressure adjustment method for ships and storage tanks in ships according to the present invention can suppress the formation of dry ice and facilitate the smooth application of storage tanks. Attached Figure Description

[0020] Figure 1 This is a top view showing the general structure of the ship involved in the embodiments of the present invention.

[0021] Figure 2 This is a diagram showing a schematic structure of the carbon dioxide injection unit according to an embodiment of the present invention.

[0022] Figure 3 This is a diagram showing the hardware structure of the control device for the carbon dioxide injection unit according to an embodiment of the present invention.

[0023] Figure 4 This is a functional block diagram of the control device involved in the embodiments of the present invention.

[0024] Figure 5 This is a flowchart illustrating the steps of a pressure adjustment method for a storage tank in a ship according to an embodiment of the present invention. Detailed Implementation

[0025] Hereinafter, with reference to the accompanying drawings, the ship involved in the embodiments of the present invention will be described.

[0026] (The overall structure of the ship)

[0027] Figure 1 This is a top view showing the general structure of the ship involved in the embodiments of the present invention. Figure 2 This is a diagram showing a schematic structure of the carbon dioxide injection unit according to an embodiment of the present invention.

[0028] like Figure 1 , Figure 2 As shown, the vessel 1 in this embodiment mainly includes a hull 2, a storage tank 10, and a carbon dioxide injection unit 20. The vessel 1 transports liquefied carbon dioxide.

[0029] like Figure 1 As shown, the hull 2 ​​has a pair of hull sides 3A and 3B that constitute its outer shell, and a bottom (not shown). The hull sides 3A and 3B have a pair of hull plating that respectively form the port and starboard sides. The bottom (not shown) has a bottom plating that connects these hull sides 3A and 3B. Through these pair of hull sides 3A and 3B and the bottom (not shown), the outer shell of the hull 2 ​​has a U-shaped cross section orthogonal to the bow-stern direction FA.

[0030] The hull 2 ​​also has an upper deck 5, which is a full-length deck located on the topmost level. A superstructure 7 is formed on this upper deck 5. Living quarters and the like are provided in the superstructure 7. In the ship 1 of this embodiment, for example, a cargo space 8 for loading cargo is provided on the bow 2a side, which is closer to the bow in the bow-stern direction than the superstructure 7.

[0031] (Structure of the storage tank)

[0032] Storage tanks 10 are installed on the hull 2. Multiple storage tanks 10 are arranged along the bow-stern direction FA within the cargo space 8. In an embodiment of the invention, two storage tanks 10 are arranged at intervals along the bow-stern direction FA. Figure 2 As shown, storage tank 10 stores liquefied carbon dioxide L inside it. The pressure inside storage tank 10 is, for example, about 0.55 to 2.0 MPaG. The temperature of the liquefied carbon dioxide L stored in storage tank 10 is, for example, about -50 to -20°C.

[0033] The storage tank 10 is, for example, a cylindrical shape extending horizontally. The storage tank 10 includes a cylindrical portion 12 and spherical end portions 13. The cylindrical portion 12 extends horizontally as its length direction. In this embodiment, the cylindrical portion 12 is formed as a cylinder with a circular cross-sectional shape orthogonal to the length direction. The spherical end portions 13 are respectively disposed at both ends of the cylindrical portion 12 along its length direction. Each spherical end portion 13 is hemispherical and closes the openings at both ends of the cylindrical portion 12 along its length direction. Furthermore, the storage tank 10 is not limited to a cylindrical shape; it can be spherical, square, or the like.

[0034] (Structure of the carbon dioxide injection section)

[0035] like Figure 2 As shown, the carbon dioxide injection unit 20 is configured to inject carbon dioxide gas G, which has a higher temperature and pressure than the carbon dioxide (liquid phase 10a and gas phase 10b) in the storage tank 10, into the storage tank 10. This carbon dioxide injection unit 20 is installed on the hull 2. The carbon dioxide injection unit 20 includes a gas storage tank 21, a first injection pipe 22, a second injection pipe 23, a pressure sensor 24, an acceleration sensor 25, and a control device 60.

[0036] The gas storage tank 21 contains carbon dioxide gas G. The pressure of the carbon dioxide gas G stored in the gas storage tank 21 is, for example, 5 to 15.7 MPaG. The temperature of the carbon dioxide gas G stored in the gas storage tank 21 is ambient temperature, for example, about 15 to 45°C. Since the gas storage tank 21 contains ambient temperature carbon dioxide gas G, it does not necessarily need to be insulated. The gas storage tank 21 can be installed in the cargo space 8, or appropriately installed on the upper deck 5 or other locations.

[0037] The first injection pipe 22 and the second injection pipe 23 respectively form flow paths for injecting carbon dioxide gas G from the gas storage tank 21 into the storage tank 10. The base ends of the first injection pipe 22 and the second injection pipe 23 are respectively connected to the gas storage tank 21. The front end 22s of the first injection pipe 22 opens into the gas phase 10b inside the storage tank 10 at the upper part of the storage tank 10. The front end 23s of the second injection pipe 23 opens into the liquid phase 10a (liquefied carbon dioxide L) inside the storage tank 10 at the bottom of the storage tank 10.

[0038] The first injection pipe 22 is equipped with an on / off valve 22v, and the second injection pipe 23 is equipped with an on / off valve 23v. Carbon dioxide gas G is intermittently injected into the storage tank 10 via the first injection pipe 22 by opening and closing the on / off valve 22v, and intermittently injected into the storage tank 10 via the second injection pipe 23 by opening and closing the on / off valve 23v. In this embodiment, the opening and closing of the on / off valves 22v and 23v is automatically controlled by the control device 60. Alternatively, the opening and closing of the on / off valves 22v and 23v can also be performed manually by an operator.

[0039] Pressure sensor 24 acquires information related to the pressure within storage tank 10. More specifically, pressure sensor 24 detects the pressure of the gas phase 10b within storage tank 10. Pressure sensor 24 outputs the detected pressure data to control device 60.

[0040] Accelerometer 25 acquires information related to the sloshing of liquid phase 10a within storage tank 10. In this embodiment, accelerometer 25 detects the acceleration caused by the sloshing of hull 2 ​​as information related to the sloshing of liquid phase 10a within storage tank 10. Accelerometer 25 may detect, for example, acceleration caused by pitting in the bow-stern direction FA of hull 2 ​​or rolling in the beam direction of hull 2. Accelerometer 25 may be installed at multiple locations on hull 2. Accelerometer 25 outputs the detected acceleration data to control device 60.

[0041] (Hardware structure diagram)

[0042] like Figure 3 As shown, the control device 60 is a computer equipped with a CPU 61 (Central Processing Unit), ROM 62 (Read Only Memory), RAM 63 (Random Access Memory), HDD 64 (Hard Disk Drive), and a signal receiving module 65. The signal receiving module 65 receives detection signals from the pressure sensor 24 and the accelerometer 25.

[0043] (Functional block diagram)

[0044] like Figure 4 As shown, the CPU 61 of the control device 60 implements the functional structures of the signal input unit 70, the determination unit 71, the opening and closing control unit 72, and the output unit 75 by executing programs pre-stored in HDD 64 or ROM 62.

[0045] The signal input unit 70 receives detection signals from the pressure sensor 24 and the acceleration sensor 25 via the signal receiving module 65, namely, the detection value of the pressure of the gas phase 10b in the storage tank 10 and the detection value of the acceleration caused by the swaying of the hull 2.

[0046] The determination unit 71 determines whether carbon dioxide gas G needs to be injected from the gas storage tank 21 into the storage tank 10 based on the detection signals received from the pressure sensor 24 and the acceleration sensor 25 by the signal input unit 70.

[0047] The opening and closing control unit 72 controls the opening and closing of the opening and closing valves 22v and 23v based on the determination result of whether carbon dioxide gas G needs to be injected in the determination unit 71. The opening and closing control unit 72 sends the control signals for opening and closing the opening and closing valves 22v and 23v to the output unit 75.

[0048] The output unit 75 outputs the control signal sent from the opening and closing control unit 72 to the opening and closing valves 22V and 23V.

[0049] (Steps for adjusting the pressure of a storage tank)

[0050] like Figure 5 As shown, the pressure adjustment method S1 of the storage tank 10 according to the embodiment of the present invention includes a step S2 of acquiring information, a step S3 of determining whether injection is required, a step S4 of injecting carbon dioxide gas into the storage tank, and a step S5 of stopping the injection of carbon dioxide gas.

[0051] In the information acquisition step S2, the control device 60 acquires detection signals from the pressure sensor 24 and the acceleration sensor 25. These detection signals are received by the signal input unit 70. The control device 60 acquires the detected pressure value of the gas phase 10b within the storage tank 10 from the pressure sensor 24 as information related to the pressure within the storage tank 10. The control device 60 acquires the detected acceleration value caused by the swaying of the hull 2 ​​from the acceleration sensor 25 as information related to the swaying of the liquefied carbon dioxide L stored in the storage tank 10.

[0052] In step S3, which determines whether injection is necessary, the control device 60 determines, via the determination unit 71, whether carbon dioxide gas G needs to be injected from the gas storage tank 21 into the storage tank 10. In this determination unit 71, the determination is based on at least one of information obtained in step S2 related to the pressure within the storage tank 10 and information related to the sloshing of liquefied carbon dioxide L stored within the storage tank 10.

[0053] In the determination unit 71, for example, when the pressure inside the storage tank 10 reaches below a preset lower pressure limit, it is determined that carbon dioxide gas G needs to be injected into the storage tank 10. The preset lower pressure limit is set to be above or above the triple point pressure of liquefied carbon dioxide L. Furthermore, for example, when the acceleration generated by the hull 2 ​​reaches above or above a preset threshold, the determination unit 71 determines that carbon dioxide gas G needs to be injected into the storage tank 10.

[0054] Here, the state where the acceleration of the hull 2 ​​reaches or exceeds a preset threshold refers to the state where the sloshing of the liquefied carbon dioxide L stored in the storage tank 10 reaches or exceeds a specified level. Thus, when the sloshing of the liquefied carbon dioxide L stored in the storage tank 10 reaches or exceeds the specified level, the static pressure inside the tank decreases due to the sloshing, and therefore the liquefied carbon dioxide L in the tank may solidify. In other words, for example, when the acceleration of the hull 2 ​​is less than the preset threshold, the solidification of the liquefied carbon dioxide L caused by the sloshing of the liquefied carbon dioxide L stored in the storage tank 10 will not actually occur.

[0055] That is, for example, the determination unit 71 determines that carbon dioxide gas G needs to be injected into the storage tank 10 when the pressure inside the storage tank 10 is below the lower pressure limit but the acceleration generated in the hull 2 ​​reaches or exceeds a threshold. Furthermore, the determination unit 71 determines that carbon dioxide gas G needs to be injected into the storage tank 10 when the pressure inside the storage tank 10 is below the lower pressure limit but the acceleration generated in the hull 2 ​​does not reach or exceed the threshold. Alternatively, the determination unit 71 can also determine that carbon dioxide gas G needs to be injected into the storage tank 10 when the pressure inside the storage tank 10 is below the lower pressure limit and the acceleration generated in the hull 2 ​​is above the threshold. Moreover, the determination unit 71 can also determine whether carbon dioxide gas G needs to be injected based on a pre-defined mapping, table, formula, or other method that establishes a correlation between the pressure inside the storage tank 10 and the acceleration generated in the hull 2.

[0056] The result of the above process S3 determines that it is unnecessary to inject carbon dioxide gas G into storage tank 10. Figure 5 If the result of step S3 is "No", return to step S2. On the other hand, if the result of step S3 determines that carbon dioxide gas G needs to be injected into storage tank 10 (…), then… Figure 5If the condition is "yes", proceed to step S4, which involves injecting carbon dioxide gas into the storage tank.

[0057] In step S4, carbon dioxide gas is injected into the storage tank from the gas storage tank 21 into the storage tank 10. As a result, the control signal for opening and closing valves 22V and 23V is output to the opening and closing valves 22V and 23V via the output unit 75 through the opening and closing control unit 72.

[0058] Here, the on / off control unit 72 can open both on / off valves 22v and 23v to inject carbon dioxide gas G from the gas storage tank 21 into the storage tank 10 through both the first injection pipe 22 and the second injection pipe 23. Furthermore, the on / off control unit 72 can also open only on / off valve 22v and inject carbon dioxide gas G from the gas storage tank 21 into the gas phase 10b of the storage tank 10 through only the first injection pipe 22. Moreover, the on / off control unit 72 can also open only on / off valve 23v and inject carbon dioxide gas G from the gas storage tank 21 into the liquid phase 10a at the bottom of the storage tank 10 through only the second injection pipe 23.

[0059] When carbon dioxide gas G is injected into storage tank 10, the temperature and pressure of carbon dioxide gas G are higher than those of carbon dioxide (including both liquid phase 10a and gas phase 10b) inside storage tank 10, thus causing the temperature and pressure inside storage tank 10 to rise. When dry ice D is generated inside storage tank 10, the dry ice D sublimates due to the increase in temperature and pressure inside storage tank 10.

[0060] In step S5, which stops the injection of carbon dioxide gas, the injection of carbon dioxide gas G from storage tank 21 to storage tank 10 is stopped when a preset injection termination condition is met. For example, the control device 60 stops the injection of carbon dioxide gas G when the pressure in storage tank 10 detected by pressure sensor 24 exceeds a lower pressure limit or exceeds a set value that is set above the lower pressure limit. When the injection of carbon dioxide gas G is stopped, the on / off control unit 72 outputs control signals for closing on / off valves 22v and 23v via output unit 75 to on / off valves 22v and 23v. When on / off valves 22v and 23v are closed, the injection of carbon dioxide gas G from storage tank 21 to storage tank 10 is stopped. When the injection of carbon dioxide gas G through the above-described step S5 is stopped, the process returns to step S2 and repeats the above series of steps.

[0061] (Effects)

[0062] The ship 1 described above includes: a hull 2; a storage tank 10 disposed on the hull 2 ​​and storing liquefied carbon dioxide L; and a carbon dioxide injection unit 20 disposed on the hull 2 ​​and capable of injecting carbon dioxide gas G, which has a higher temperature and pressure than the carbon dioxide (liquid phase 10a and gas phase 10b) in the storage tank 10, into the storage tank 10.

[0063] According to this type of vessel 1, when the liquefied carbon dioxide L stored in the storage tank 10 is in a state of generating dry ice D, carbon dioxide gas G can be injected into the storage tank 10 by the carbon dioxide injection unit 20. Furthermore, the temperature and pressure of the carbon dioxide gas G are higher than those of the carbon dioxide (including both liquid phase 10a and gas phase 10b) in the storage tank 10, thus preventing pressure drop within the storage tank 10. Moreover, when dry ice D is generated in the storage tank 10, the dry ice D can be sublimated by the carbon dioxide gas G.

[0064] Therefore, the formation of dry ice D can be suppressed, allowing the storage tank 10 to be used smoothly.

[0065] Furthermore, in the ship 1 described above, the carbon dioxide injection unit 20 is configured to inject carbon dioxide gas G into the gas phase 10b of carbon dioxide in the storage tank 10.

[0066] Therefore, by injecting carbon dioxide gas G into the gas phase 10b of carbon dioxide in the storage tank 10 through the carbon dioxide injection unit 20, the pressure inside the storage tank 10 can be increased immediately.

[0067] Furthermore, in the ship 1 described above, the carbon dioxide injection unit 20 is configured to inject carbon dioxide gas G into the liquid phase 10a of carbon dioxide in the storage tank 10.

[0068] Therefore, by injecting carbon dioxide gas G into the liquid phase 10a of carbon dioxide in the storage tank 10 through the carbon dioxide injection unit 20, and generating dry ice D in the liquid phase 10a of carbon dioxide, carbon dioxide gas G can be introduced around the dry ice D. Moreover, through the injected carbon dioxide gas G, the liquid phase 10a of carbon dioxide around the dry ice D vaporizes, thereby increasing the pressure inside the storage tank 10 and promoting the sublimation of the dry ice D.

[0069] Furthermore, in the above embodiment, the front end 23s of the second injection pipe 23 of the carbon dioxide injection unit 20 opens at the bottom of the storage tank 10 to the liquid phase 10a (liquefied carbon dioxide L) inside the storage tank 10.

[0070] For example, when dry ice D is generated inside storage tank 10, it tends to accumulate at the bottom of storage tank 10 because its density is higher than that of liquefied carbon dioxide. In contrast, as described above, by opening a carbon dioxide gas G at the bottom of storage tank 10 through the front end 23s of the second injection pipe 23 of carbon dioxide injection section 20, the dry ice D accumulated at the bottom can be rapidly sublimated by injecting carbon dioxide gas G at a position close to the dry ice D accumulated at the bottom.

[0071] Furthermore, in the ship 1 of the above embodiment, when the pressure of the carbon dioxide injection unit 20 in the storage tank 10 reaches or falls below the lower limit of the pressure set above or above the triple point pressure of liquefied carbon dioxide L, carbon dioxide gas G is injected into the storage tank 10.

[0072] Therefore, when the pressure inside the storage tank 10 is below the lower pressure limit and the storage tank 10 is in a state where dry ice D is easily generated, injecting carbon dioxide gas G into the storage tank 10 can suppress the generation of dry ice D inside the storage tank 10.

[0073] Furthermore, in the ship 1 described above, carbon dioxide gas G is injected into the storage tank 10 when the sloshing of liquefied carbon dioxide L stored in the storage tank 10 reaches a predetermined level or above.

[0074] Therefore, when the sloshing of liquefied carbon dioxide L stored in tank 10 reaches a specified level or above, the pressure inside tank 10 can be increased, thereby suppressing the formation of dry ice D inside tank 10.

[0075] The pressure adjustment method S1 of the storage tank 10 described above includes: a step S2 of acquiring at least one of information related to the pressure inside the storage tank 10 and information related to the sloshing of liquefied carbon dioxide L stored in the storage tank 10; and a step S4 of injecting carbon dioxide gas G into the storage tank 10 by the carbon dioxide injection unit 20 according to the acquired information.

[0076] Therefore, based on the pressure inside the storage tank 10 and the sloshing state of the liquefied carbon dioxide stored in the storage tank 10, carbon dioxide gas G can be injected into the storage tank 10, thus suppressing the formation of dry ice D and enabling the smooth application of the storage tank 10.

[0077] (Other implementation methods)

[0078] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments and may include design changes that do not depart from the spirit of the present invention.

[0079] In addition, the ship 1 described above is provided with a first injection pipe 22 and a second injection pipe 23, but it is also possible to provide only one of the first injection pipe 22 and the second injection pipe 23.

[0080] In the ship 1 described above, a pressure sensor 24 is provided to obtain information related to the pressure inside the storage tank 10. However, it is also possible to detect not only the pressure inside the storage tank 10 but also the temperature of the gas phase 10b inside the storage tank 10, and determine whether carbon dioxide gas G needs to be injected into the storage tank 10 based on the pressure and temperature inside the storage tank 10.

[0081] In the ship 1 described above, an acceleration sensor 25 is provided in order to obtain information related to the sloshing of the liquid phase 10a in the storage tank 10. However, any structure that can detect the sloshing of the liquid phase 10a in the storage tank 10 is acceptable. For example, it can also be configured to detect the change in the liquid level of the liquid phase 10a in the storage tank 10.

[0082] The steps of the above-mentioned pressure adjustment method for storage tanks can be appropriately modified in terms of specific judgment content and the order of steps.

[0083] <Appendix>

[0084] The pressure adjustment method S1 of the ship 1 and the storage tank 10 in the ship 1 described in the implementation method can be understood as follows, for example.

[0085] (1) The vessel 1 involved in the first method includes: a hull 2; a storage tank 10, which is provided on the hull 2 ​​and stores liquefied carbon dioxide L; and a carbon dioxide injection unit 20, which is provided on the hull 2 ​​and is capable of injecting carbon dioxide gas G with a temperature and pressure higher than that of the carbon dioxide in the storage tank 10 into the storage tank 10.

[0086] According to the vessel 1, the carbon dioxide injection unit 20 can inject carbon dioxide gas G, which has a higher temperature and pressure than the carbon dioxide in the storage tank 10, into the storage tank 10. When the liquefied carbon dioxide L stored in the storage tank 10 is in a state of forming dry ice D, the carbon dioxide injection unit 20 injects carbon dioxide gas G into the storage tank 10. The temperature and pressure of the carbon dioxide gas G are higher than those of the carbon dioxide in the storage tank 10 (including both liquid phase 10a and gas phase 10b), thus preventing the pressure drop in the storage tank 10. Furthermore, when dry ice D is formed in the storage tank 10, the carbon dioxide gas G can sublimate the dry ice D.

[0087] Therefore, the formation of dry ice D can be suppressed, allowing the storage tank 10 to be used smoothly.

[0088] (2) The vessel 1 involved in the second method is the vessel 1 of (1), wherein the carbon dioxide injection unit 20 injects the carbon dioxide gas G into the gas phase 10b of carbon dioxide in the storage tank 10.

[0089] Therefore, by injecting carbon dioxide gas G into the gas phase 10b of carbon dioxide in the storage tank 10 through the carbon dioxide injection unit 20, the pressure inside the storage tank 10 can be increased immediately.

[0090] (3) The vessel 1 involved in the third method is the vessel 1 of (1) or (2), wherein the carbon dioxide injection unit 20 injects the carbon dioxide gas G into the liquid phase 10a of carbon dioxide in the storage tank 10.

[0091] Therefore, by injecting carbon dioxide gas G into the liquid phase 10a of carbon dioxide in the storage tank 10 through the carbon dioxide injection unit 20, and when dry ice D is generated in the liquid phase 10a of carbon dioxide, carbon dioxide gas G can be introduced around the dry ice D. Through the injected carbon dioxide gas G, the liquid phase 10a of carbon dioxide around the dry ice D vaporizes, thereby increasing the pressure inside the storage tank 10 and promoting the sublimation of the dry ice D.

[0092] (4) The vessel 1 involved in the fourth method is any one of (1) to (3), wherein when the pressure of the carbon dioxide injection unit 20 in the storage tank 10 reaches or falls below the lower limit of the pressure set above or above the triple point pressure of the liquefied carbon dioxide L, the carbon dioxide gas G is injected into the storage tank 10.

[0093] Therefore, by injecting carbon dioxide gas G into the storage tank 10 when the pressure inside the storage tank 10 is below the lower pressure limit and the storage tank 10 is in a state where dry ice D is easily generated, the generation of dry ice D in the storage tank 10 can be suppressed.

[0094] (5) The vessel 1 involved in the fifth method is any one of (1) to (4) and wherein the carbon dioxide injection unit 20 injects the carbon dioxide gas G into the storage tank 10 when the sloshing of the liquefied carbon dioxide L stored in the storage tank 10 reaches a specified level or above.

[0095] Therefore, by injecting carbon dioxide gas G into the storage tank 10 when the sloshing of liquefied carbon dioxide L stored in the storage tank 10 reaches a specified level or above, the pressure inside the storage tank 10 can be increased, thereby suppressing the formation of dry ice D inside the storage tank 10.

[0096] The sloshing of liquefied carbon dioxide L stored in tank 10 is detected by detecting the acceleration caused by the sloshing of the ship 2 and the change in the liquid level of liquefied carbon dioxide L in tank 10.

[0097] (6) The pressure adjustment method S1 of the storage tank 10 in the ship 1 involved in the sixth method is any one of (1) to (5) of the pressure adjustment method S1 of the storage tank 10 in the ship 1, which includes: a step S2 of obtaining at least one of the information related to the pressure in the storage tank 10 and the information related to the sloshing of the liquefied carbon dioxide L stored in the storage tank 10; and a step S4 of injecting the carbon dioxide gas G into the storage tank 10 by the carbon dioxide injection unit 20 according to the obtained information.

[0098] Therefore, by injecting carbon dioxide gas G into the storage tank 10 according to the pressure inside the storage tank 10 and the sloshing state of the liquefied carbon dioxide stored in the storage tank 10, the formation of dry ice D can be suppressed and the storage tank 10 can be used smoothly.

[0099] Information relating to the pressure inside the storage tank 10 may include the pressure value inside the storage tank 10 and the temperature of the gas phase 10b inside the storage tank 10.

[0100] Information relating to the sloshing of liquefied carbon dioxide L stored in tank 10 can include the measured value of the acceleration caused by the sloshing of the hull 2 ​​and the measured value of the change in the liquid level of liquefied carbon dioxide L in tank 10.

[0101] Industrial availability

[0102] Using the above method, the formation of dry ice can be suppressed, allowing for the smooth application of storage tanks.

[0103] Symbol Explanation

[0104] 1-Ship, 2-Hull, 2a-Bow, 3A, 3B-Side of the ship, 5-Upper deck, 7-Superstructure, 8-Cargo space, 10-Storage tank, 10a-Liquid phase, 10b-Gas phase, 12-Cylindrical section, 13-Spherical end section, 20-Carbon dioxide injection section, 21-Gas storage tank, 22-First injection piping, 22s-Front end, 22v-On / off valve, 23-Second injection piping, 23s-Front end, 23v-On / off valve, 24-Pressure sensor, 25-Acceleration sensor, 60-Control device, 61-CPU, 62-ROM, 63-RAM, 64-HDD, 65-Signal receiving module, 70-Signal input section, 71-Decision section, 72-On / off control section, 75-Output section, FA-Bow / stern direction, D-Dry ice, G-Carbon dioxide gas, L-Liquefied carbon dioxide.

Claims

1. A ship having: hull; Storage tanks, located within the hull, store liquefied carbon dioxide; and A carbon dioxide injection unit, located within the hull, is capable of injecting carbon dioxide gas with a temperature and pressure higher than that inside the storage tank into the storage tank. When the sloshing of the liquefied carbon dioxide stored in the tank reaches a predetermined level, the carbon dioxide injection unit injects the carbon dioxide gas into the tank.

2. The vessel according to claim 1, wherein, The carbon dioxide injection unit injects the carbon dioxide gas into the gas phase of the carbon dioxide in the storage tank.

3. The vessel according to claim 1 or 2, wherein, The carbon dioxide injection unit injects the carbon dioxide gas into the liquid phase of the carbon dioxide in the storage tank.

4. The vessel according to claim 1 or 2, wherein, When the pressure inside the storage tank reaches a lower limit value that is set above or below the triple point pressure of the liquefied carbon dioxide, the carbon dioxide injection unit injects the carbon dioxide gas into the storage tank.

5. A method for adjusting the pressure of a storage tank in a ship, as described in any one of claims 1 to 4, comprising: The process of obtaining at least one of information relating to the pressure inside the storage tank and information relating to the sloshing of the liquefied carbon dioxide stored in the storage tank; and The process of injecting carbon dioxide gas into the storage tank by the carbon dioxide injection unit based on the obtained information.

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