JP7699454B2 - Method for adjusting tank pressure on ships and vessels - Google Patents

Description

This disclosure relates to ships and methods for adjusting tank pressure on ships.

Patent Document 1 discloses a configuration for transporting dry ice that has been precipitated by spraying liquid carbon dioxide inside a ship's hold.

Furthermore, Patent Document 2 discloses transporting carbon dioxide in the form of compressed carbon dioxide gas under a tank pressure of 15 kg/cm ² and at room temperature (for example, 0 to 30° C.).

Japanese Patent Application Publication No. 5-180394 JP 2004-125039 A

However, when liquefied carbon dioxide is stored in a tank installed in the hull, it may solidify and produce dry ice for the following reasons. In other words, the pressure of the liquefied carbon dioxide in the tank depends on the tank operating pressure. The pressure of the triple point (triple point pressure) of liquefied carbon dioxide, where the gas, liquid, and solid phases coexist, is higher than the triple point pressure of liquefied gas (LNG: Liquid Natural Gas) or liquefied petroleum gas (LPG: Liquid Petroleum Gas), and there is a possibility that the triple point will be reached if the tank is depressurized during operation.

When the pressure of liquefied carbon dioxide falls below the triple point pressure, flash evaporation of the liquefied carbon dioxide can occur. If this occurs, the latent heat of vaporization of the liquefied carbon dioxide flash evaporation will cause a drop in the temperature of the liquefied carbon dioxide that remains unevaporated, which may cause the liquefied carbon dioxide to solidify in the tank and produce dry ice. For this reason, the tank operating pressure (tank design pressure) is set so that the pressure of the liquefied carbon dioxide does not fall below the triple point pressure. However, if the tank operating pressure is set significantly higher than the triple point pressure of liquefied carbon dioxide, the tank itself and the piping connected to the tank must be designed to withstand pressure according to the tank operating pressure (tank design pressure), which will lead to increased costs.

In addition, for example, when the liquefied carbon dioxide in the tank sways due to the rocking of the ship's hull, the dynamic pressure of the liquefied carbon dioxide increases according to the flow rate of the liquefied carbon dioxide, and the static pressure of the liquefied carbon dioxide decreases. This decrease in the static pressure of the liquefied carbon dioxide in the tank may cause the liquefied carbon dioxide to solidify in the tank, producing dry ice.
Furthermore, because the density of dry ice is greater than that of liquefied carbon dioxide, once dry ice is generated inside a tank, it will settle and accumulate at the bottom of the tank, and even after the pressure inside the tank is restored, it may take some time for the dry ice to sublimate.

The present disclosure has been made to solve the above problems, and aims to provide a ship and a method for adjusting tank pressure on a ship that can suppress the generation of dry ice and enable smooth tank operation.

In order to solve the above problems, a ship according to the present disclosure comprises a hull, a tank, a high-temperature, high-pressure gas tank, and a carbon dioxide injection unit. The tank is provided in the hull. The tank stores liquefied carbon dioxide. The high-temperature, high-pressure gas tank is provided in the hull. The high-temperature, high-pressure gas tank is capable of storing carbon dioxide gas at a higher temperature and pressure than the carbon dioxide in the tank. The carbon dioxide injection unit is capable of injecting the high-temperature, high-pressure carbon dioxide gas stored in the high-temperature , high-pressure gas tank into the tank. The carbon dioxide injection unit injects the carbon dioxide gas into the tank when the swaying of the liquefied carbon dioxide stored in the tank reaches a predetermined level.

The method for adjusting pressure in a tank in a ship according to the present disclosure is a method for adjusting pressure in a tank in a ship as described above, and includes a step of acquiring information and a step of injecting carbon dioxide gas into the tank. In the step of acquiring information, at least one of information regarding the pressure in the tank and information regarding the swaying of the liquefied carbon dioxide stored in the tank is acquired. In the step of injecting the carbon dioxide gas into the tank, the carbon dioxide gas is injected into the tank by the carbon dioxide injection unit based on the acquired information.

The ship and tank pressure adjustment method disclosed herein can reduce the generation of dry ice and facilitate smooth tank operation.

FIG. 1 is a plan view showing a schematic configuration of a ship according to an embodiment of the present disclosure. FIG. 2 is a diagram showing a schematic configuration of a carbon dioxide injection section according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating a hardware configuration of a control device of a carbon dioxide injection unit according to an embodiment of the present disclosure. FIG. 2 is a functional block diagram of a control device according to an embodiment of the present disclosure. 4 is a flowchart showing the steps of a tank pressure adjustment method in a ship according to an embodiment of the present disclosure.

Hereinafter, a vessel according to an embodiment of the present disclosure will be described with reference to the drawings.
(Overall configuration of the vessel)
Fig. 1 is a plan view showing a schematic configuration of a ship according to an embodiment of the present disclosure Fig. 2 is a diagram showing a schematic configuration of a carbon dioxide injection unit according to an embodiment of the present disclosure.
1 and 2, a ship 1 of this embodiment mainly includes a hull 2, a tank 10, and a carbon dioxide injection section 20. The ship 1 transports liquefied carbon dioxide.

As shown in FIG. 1, the hull 2 has a pair of side panels 3A, 3B and a bottom panel (not shown) that form its outer hull. The side panels 3A, 3B each have a pair of side panel shells that form the starboard and port sides, respectively. The bottom panel (not shown) has a bottom panel shell that connects the side panels 3A, 3B. The pair of side panels 3A, 3B and the bottom panel (not shown) give the outer hull 2 a U-shape in a cross section perpendicular to the bow-stern direction FA.

The hull 2 further includes an upper deck 5, which is a full-length deck located at the topmost level. A superstructure 7 is formed on the upper deck 5. Accommodation areas and the like are provided within the superstructure 7. In the ship 1 of this embodiment, for example, a cargo space 8 for carrying cargo is provided closer to the bow 2a in the bow-stern direction FA than the superstructure 7.

(Tank configuration)
The tank 10 is provided in the hull 2. A plurality of the tanks 10 are arranged in the cargo space 8 along the bow-stern direction FA. In the embodiment of the present disclosure, two tanks 10 are arranged at an interval in the bow-stern direction FA. As shown in FIG. 2 , the tank 10 stores liquefied carbon dioxide L therein. The pressure in the tank 10 is, for example, about 0.55 to 2.0 MPaG. The temperature of the liquefied carbon dioxide L stored in the tank 10 is, for example, about -50 to -20°C.

The tank 10 is, for example, cylindrical and extends in the horizontal direction. The tank 10 includes a tubular portion 12 and an end spherical portion 13. The tubular portion 12 extends in the horizontal direction as the longitudinal direction. In this embodiment, the tubular portion 12 is formed in a cylindrical shape with a circular cross section perpendicular to the longitudinal direction. The end spherical portions 13 are disposed at both ends of the tubular portion 12 in the longitudinal direction. Each end spherical portion 13 is semispherical and closes the openings at both ends of the tubular portion 12 in the longitudinal direction. Note that the tank 10 is not limited to being cylindrical, and the tank 10 may be spherical, rectangular, or the like.

(Configuration of carbon dioxide injection section)
2, the carbon dioxide injection unit 20 is configured to be able 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 tank 10, into the tank 10. The carbon dioxide injection unit 20 is provided in the hull 2. The carbon dioxide injection unit 20 includes a gas 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.

The gas tank 21 stores carbon dioxide gas G. The pressure of the carbon dioxide gas G stored in the gas tank 21 is, for example, 5 to 15.7 MPaG. The temperature of the carbon dioxide gas G stored in the gas tank 21 is room temperature, for example, about 15 to 45°C. Since the gas tank 21 stores carbon dioxide gas G at room temperature, it does not necessarily need to be heat-insulated. The gas tank 21 may be provided in the cargo space 8, or may be provided in another appropriate location, such as on the upper deck 5.

The first injection pipe 22 and the second injection pipe 23 each form a flow path for injecting carbon dioxide gas G from the gas tank 21 into the tank 10. The base end of the first injection pipe 22 and the base end of the second injection pipe 23 are each connected to the gas tank 21. The tip 22s of the first injection pipe 22 opens into the gas phase 10b in the tank 10 at the top of the tank 10. The tip 23s of the second injection pipe 23 opens into the liquid phase 10a (liquefied carbon dioxide L) in the tank 10 at the bottom of the tank 10.

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. By opening and closing the on-off valve 22v, the injection of carbon dioxide gas G into the tank 10 through the first injection pipe 22 is interrupted, and by opening and closing the on-off valve 23v, the injection of carbon dioxide gas G into the tank 10 through the second injection pipe 23 is interrupted. In this embodiment, the opening and closing operations of the on-off valves 22v and 23v are automatically controlled by the control device 60. Note that the opening and closing operations of the on-off valves 22v and 23v may be performed manually, for example, by an operator.

The pressure sensor 24 acquires information regarding the pressure inside the tank 10. More specifically, the pressure sensor 24 detects the pressure of the gas phase 10b inside the tank 10. The pressure sensor 24 outputs the detected pressure data to the control device 60.

The acceleration sensor 25 acquires information related to the sloshing of the liquid phase 10a in the tank 10. In this embodiment, the acceleration sensor 25 detects acceleration caused by the sloshing of the hull 2 as information related to the sloshing of the liquid phase 10a in the tank 10. The acceleration sensor 25 detects, for example, acceleration caused by the sloshing of the hull 2 in the bow-stern direction FA (pitching) and the sloshing of the hull 2 in the width direction (rolling). The acceleration sensor 25 may be provided at multiple locations on the hull 2. The acceleration sensor 25 outputs the detected acceleration data to the control device 60.

(Hardware configuration diagram)
3, the control device 60 is a computer including a central processing unit (CPU) 61, a read only memory (ROM) 62, a random access memory (RAM) 63, a hard disk drive (HDD) 64, and a signal receiving module 65. The signal receiving module 65 receives detection signals from the pressure sensor 24 and the acceleration sensor 25.

(Function block diagram)
As shown in FIG. 4, the CPU 61 of the control device 60 executes a program stored in advance in the HDD 64, the ROM 62, etc., to realize the respective functional components of the signal input unit 70, the determination unit 71, the opening/closing control unit 72, and the output unit 75.
The signal input unit 70 receives detection signals from the pressure sensor 24 and the acceleration sensor 25, i.e., data on the detected pressure of the gas phase 10b in the tank 10 and data on the detected acceleration caused by the rocking of the hull 2, via the signal receiving module 65.

The determination unit 71 determines whether or not it is necessary to inject carbon dioxide gas G from the gas tank 21 into the tank 10 based on the detection signals received by the signal input unit 70 from the pressure sensor 24 and the acceleration sensor 25 .
The opening/closing control unit 72 controls the opening and closing of the on-off valve 22v and the opening and closing of the on-off valve 23v based on the determination result of the determination unit 71 as to whether or not it is necessary to inject the carbon dioxide gas G. The opening/closing control unit 72 sends a control signal for opening and closing the on-off valves 22v, 23v to the output unit 75.
The output unit 75 outputs the control signal sent from the opening/closing control unit 72 to the opening/closing valves 22v and 23v.

(Tank pressure adjustment procedure)
As shown in FIG. 5, a method S1 for adjusting pressure of the tank 10 according to an embodiment of the present disclosure includes a step S2 of acquiring information, a step S3 of determining whether injection is necessary, a step S4 of injecting carbon dioxide gas into the tank, and a step S5 of stopping the injection of carbon dioxide gas.

In the information acquisition step S2, the control device 60 acquires detection signals from the pressure sensor 24 and acceleration sensor 25. The detection signals from the pressure sensor 24 and acceleration sensor 25 are received by the signal input unit 70. The control device 60 acquires the detection value of the pressure of the gas phase 10b in the tank 10 from the pressure sensor 24 as information related to the pressure in the tank 10. The control device 60 acquires the detection value of the acceleration due to the rocking of the hull 2 from the acceleration sensor 25 as information related to the rocking of the liquefied carbon dioxide L stored in the tank 10.

In step S3 of determining whether or not injection is necessary, the control device 60 uses the determination unit 71 to determine whether or not injection of carbon dioxide gas G from the gas tank 21 to the tank 10 is necessary. This determination unit 71 determines whether or not injection of carbon dioxide gas G is necessary based on at least one of the information regarding the pressure inside the tank 10 acquired in step S2 and the information regarding the swaying of the liquefied carbon dioxide L stored in the tank 10.

The determination unit 71 determines that it is necessary to inject carbon dioxide gas G into the tank 10, for example, when the pressure inside the tank 10 becomes equal to or lower than a predetermined lower pressure limit. The predetermined lower pressure limit is set to be equal to or higher than the triple point pressure of liquefied carbon dioxide L. Furthermore, the determination unit 71 determines that it is necessary to inject carbon dioxide gas G into the tank 10, for example, when the acceleration generated in the hull 2 becomes equal to or higher than a predetermined threshold value.

Here, the state in which the acceleration generated in the hull 2 is equal to or greater than a predetermined threshold value means a state in which the swaying of the liquefied carbon dioxide L stored in the tank 10 is equal to or greater than a predetermined level. In this state in which the swaying of the liquefied carbon dioxide L stored in the tank 10 is equal to or greater than a predetermined level, the swaying of the liquefied carbon dioxide L stored in the tank 10 may cause a drop in the static pressure in the tank, which may cause the liquefied carbon dioxide L in the tank to solidify. In other words, for example, when the acceleration generated in the hull 2 is smaller than a predetermined threshold value, the liquefied carbon dioxide L will not substantially solidify due to the swaying of the liquefied carbon dioxide L stored in the tank 10.

That is, for example, the determination unit 71 determines that it is necessary to inject carbon dioxide gas G into the tank 10 when the acceleration occurring in the hull 2 is equal to or greater than a threshold value even if the pressure in the tank 10 is not equal to or less than the pressure lower limit. The determination unit 71 determines that it is necessary to inject carbon dioxide gas G into the tank 10 if the pressure in the tank 10 is equal to or less than the pressure lower limit, even if the acceleration occurring in the hull 2 is not equal to or greater than a threshold value. The determination unit 71 may determine that it is necessary to inject carbon dioxide gas G into the tank 10 when the pressure in the tank 10 is equal to or less than the pressure lower limit and the acceleration occurring in the hull 2 is equal to or greater than a threshold value. The determination unit 71 may also determine whether or not it is necessary to inject carbon dioxide gas G based on a map, table, formula, or the like that is preset based on the correlation between the pressure in the tank 10 and the acceleration occurring in the hull 2.

If it is determined in step S3 that there is no need to inject carbon dioxide gas G into the tank 10 ("No" in FIG. 5), the process returns to step S2 described above. On the other hand, if it is determined in step S3 that there is a need to inject carbon dioxide gas G into the tank 10 ("Yes" in FIG. 5), the process returns to step S4 of injecting carbon dioxide gas into the tank.

In step S4 of injecting carbon dioxide gas into the tank, carbon dioxide gas G is injected from the gas tank 21 into the tank 10. To do this, the opening/closing control unit 72 outputs a control signal to open the opening/closing valves 22v, 23v via the output unit 75 to the opening/closing valves 22v, 23v.

Here, the opening/closing control unit 72 may open both the opening/closing valves 22v and 23v and inject carbon dioxide gas G from the gas tank 21 into the tank 10 through both the first injection pipe 22 and the second injection pipe 23. The opening/closing control unit 72 may also open only the opening/closing valve 22v and inject carbon dioxide gas G from the gas tank 21 into the gas phase 10b of the tank 10 through only the first injection pipe 22. The opening/closing control unit 72 may further open only the opening/closing valve 23v and inject carbon dioxide gas G from the gas tank 21 into the liquid phase 10a at the bottom of the tank 10 through only the second injection pipe 23.

When carbon dioxide gas G is injected into tank 10, the temperature and pressure inside tank 10 rise because carbon dioxide gas G is at a higher temperature and pressure than the carbon dioxide (including both liquid phase 10a and gas phase 10b) inside tank 10. If dry ice D has been generated inside tank 10, the rise in temperature and pressure inside tank 10 causes the dry ice D to sublime.

In step S5 of stopping the injection of carbon dioxide gas, when a preset injection end condition is satisfied, the control device 60 stops the injection of carbon dioxide gas G from the gas tank 21 to the tank 10. For example, when the pressure in the tank 10 detected by the pressure sensor 24 exceeds the lower pressure limit value or exceeds a set value set to be equal to or higher than the lower pressure limit value, the control device 60 stops the injection of carbon dioxide gas G. When stopping the injection of carbon dioxide gas G, the opening/closing control unit 72 outputs a control signal for closing the opening/closing valves 22v, 23v to the opening/closing valves 22v, 23v via the output unit 75. When the opening/closing valves 22v, 23v are closed, the injection of carbon dioxide gas G from the gas tank 21 to the tank 10 stops. When the injection of carbon dioxide gas G by the above step S5 stops, the process returns to step S2 and the above series of steps are repeated.

(Action and Effect)
The ship 1 of the above embodiment comprises a hull 2, a tank 10 provided in the hull 2 for storing liquefied carbon dioxide L, and a carbon dioxide injection section 20 provided in the hull 2 and capable of injecting carbon dioxide gas G, which is at a higher temperature and pressure than the carbon dioxide (liquid phase 10a and gas phase 10b) in the tank 10, into the tank 10.

According to such a ship 1, when a state occurs in which dry ice D is generated from the liquefied carbon dioxide L stored in the tank 10, the carbon dioxide gas G can be injected into the tank 10 by the carbon dioxide injection section 20. Since the carbon dioxide gas G has a higher temperature and pressure than the carbon dioxide (including both the liquid phase 10a and the gas phase 10b) in the tank 10, a pressure drop in the tank 10 can be suppressed. Furthermore, when dry ice D is generated in the tank 10, the dry ice D can be sublimated by the carbon dioxide gas G.
Therefore, the production of dry ice D can be suppressed, and the operation of the tank 10 can be carried out smoothly.

In the ship 1 of the above embodiment, the carbon dioxide injection section 20 is further configured to be able to inject carbon dioxide gas G into the carbon dioxide gas phase 10 b in the tank 10 .
Therefore, by injecting carbon dioxide gas G into the carbon dioxide gas phase 10b in the tank 10 at the carbon dioxide injection section 20, the pressure in the tank 10 can be instantly increased.

In the ship 1 of the above embodiment, the carbon dioxide injection section 20 is further configured to be able to inject carbon dioxide gas G into the carbon dioxide liquid phase 10 a in the tank 10 .
Therefore, when dry ice D is generated in the carbon dioxide liquid phase 10a by injecting carbon dioxide gas G into the carbon dioxide liquid phase 10a in the tank 10 by the carbon dioxide injection unit 20, the carbon dioxide gas G can be sent to the periphery of the dry ice D. Then, the injected carbon dioxide gas G gasifies the carbon dioxide liquid phase 10a around the dry ice D, thereby increasing the pressure inside the tank 10 and promoting the sublimation of the dry ice D.

In the above embodiment, furthermore, the tip 23 s of the second injection pipe 23 of the carbon dioxide injection section 20 opens into the liquid phase 10 a (liquefied carbon dioxide L) in the tank 10 at the bottom of the tank 10 .
For example, when dry ice D is produced in the tank 10, the dry ice D has a higher density than liquefied carbon dioxide and therefore tends to accumulate at the bottom of the tank 10. In contrast, since the tip 23s of the second injection pipe 23 of the carbon dioxide injection part 20 opens at the bottom of the tank 10 as described above, it is possible to inject the carbon dioxide gas G at a position closer to the dry ice D accumulated at the bottom, thereby quickly sublimating the dry ice D accumulated at the bottom.

Furthermore, in the ship 1 of the above embodiment, the carbon dioxide injection section 20 injects carbon dioxide gas G into the tank 10 when the pressure inside the tank 10 falls below a lower pressure limit value set above the triple point pressure of liquefied carbon dioxide L.
By doing this, when the pressure inside the tank 10 falls below the lower pressure limit value and the tank 10 is in a state in which dry ice D is likely to be generated, carbon dioxide gas G can be injected into the tank 10 to suppress the generation of dry ice D inside the tank 10.

In the ship 1 of the above embodiment, furthermore, when the swaying of the liquefied carbon dioxide L stored in the tank 10 reaches or exceeds a predetermined level, carbon dioxide gas G is injected into the tank 10.
Therefore, when the swaying of the liquefied carbon dioxide L stored in the tank 10 reaches or exceeds a predetermined level, the pressure within the tank 10 can be increased, thereby suppressing the generation of dry ice D within the tank 10.

The pressure adjustment method S1 of the tank 10 in the above embodiment includes a step S2 of acquiring at least one of information regarding the pressure within the tank 10 and information regarding the swaying of the liquefied carbon dioxide L stored in the tank 10, and a step S4 of injecting carbon dioxide gas G into the tank 10 using the carbon dioxide injection section 20 based on the acquired information.
In this manner, carbon dioxide gas G can be injected into tank 10 based on the pressure within tank 10 and the swaying state of the liquefied carbon stored in tank 10, thereby making it possible to suppress the production of dry ice D and operate tank 10 smoothly.

Other Embodiments
Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of the present disclosure are also included.
In the ship 1 of the above embodiment, the first injection pipe 22 and the second injection pipe 23 are provided, but only one of the first injection pipe 22 and the second injection pipe 23 may be provided.

In the above embodiment, the ship 1 was equipped with a pressure sensor 24 to obtain information regarding the pressure inside the tank 10, but it is also possible to detect not only the pressure inside the tank 10 but also the temperature of the gas phase 10b inside the tank 10, and determine whether or not to inject carbon dioxide gas G into the tank 10 based on the pressure and temperature inside the tank 10.

In the above embodiment of the ship 1, an acceleration sensor 25 was provided to obtain information regarding the sloshing of the liquid phase 10a in the tank 10, but any configuration that can detect the sloshing of the liquid phase 10a in the tank 10 will suffice, and for example, the displacement of the liquid level of the liquid phase 10a in the tank 10 may be detected.

The steps in the tank pressure adjustment method described above can be modified as appropriate in terms of the specific judgment content, order of steps, etc.

<Additional Notes>
The ship 1 and the pressure adjustment method S1 for the tank 10 in the ship 1 described in the embodiment can be understood, for example, as follows.

(1) The ship 1 according to the first aspect comprises a hull 2, a tank 10 provided in the hull 2 for storing liquefied carbon dioxide L, and a carbon dioxide injection section 20 provided in the hull 2 for injecting carbon dioxide gas G into the tank 10 at a higher temperature and pressure than the carbon dioxide in the tank 10.

According to this ship 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 tank 10, into the tank 10. When a state occurs in which dry ice D is generated from the liquefied carbon dioxide L stored in the tank 10, the carbon dioxide injection unit 20 injects the carbon dioxide gas G into the tank 10. Since the carbon dioxide gas G has a higher temperature and pressure than the carbon dioxide (including both the liquid phase 10a and the gas phase 10b) in the tank 10, a pressure drop in the tank 10 can be suppressed. Furthermore, when dry ice D is generated in the tank 10, the carbon dioxide gas G can be sublimated.
Therefore, the production of dry ice D can be suppressed, and the operation of the tank 10 can be carried out smoothly.

(2) The ship 1 according to the second aspect is the ship 1 of (1), in which the carbon dioxide injection unit 20 injects the carbon dioxide gas G into the carbon dioxide gas phase 10b in the tank 10.

This allows the pressure inside the tank 10 to be instantly increased by injecting carbon dioxide gas G into the carbon dioxide gas phase 10b inside the tank 10 using the carbon dioxide injection section 20.

(3) The ship 1 according to the third aspect is the ship 1 according to (1) or (2), and the carbon dioxide injection section 20 injects the carbon dioxide gas G into the liquid phase 10a of carbon dioxide in the tank 10.

As a result, when dry ice D is generated in the carbon dioxide liquid phase 10a by injecting carbon dioxide gas G into the carbon dioxide liquid phase 10a in the tank 10 using the carbon dioxide injection section 20, the carbon dioxide gas G can be sent to the surroundings of the dry ice D. The injected carbon dioxide gas G gasifies the carbon dioxide liquid phase 10a around the dry ice D, thereby increasing the pressure inside the tank 10 and promoting the sublimation of the dry ice D.

(4) The ship 1 according to the fourth aspect is any one of the ships 1 according to (1) to (3), and the carbon dioxide injection section 20 injects the carbon dioxide gas G into the tank 10 when the pressure inside the tank 10 becomes equal to or lower than a lower pressure limit value set to be equal to or higher than the triple point pressure of the liquefied carbon dioxide L.

As a result, when the pressure inside the tank 10 falls below the lower pressure limit and the tank 10 is in a state in which dry ice D is likely to be generated, carbon dioxide gas G can be injected into the tank 10 to suppress the generation of dry ice D inside the tank 10.

(5) The ship 1 according to the fifth aspect is any one of the ships 1 according to (1) to (4), and the carbon dioxide injection unit 20 injects the carbon dioxide gas G into the tank 10 when the swaying of the liquefied carbon dioxide L stored in the tank 10 reaches or exceeds a predetermined level.

As a result, when the swaying of the liquefied carbon dioxide L stored in the tank 10 reaches or exceeds a predetermined level, carbon dioxide gas G can be injected into the tank 10 to increase the pressure within the tank 10, thereby suppressing the generation of dry ice D within the tank 10.
The swaying of the liquefied carbon dioxide L stored in the tank 10 is detected by detecting the acceleration caused by the swaying of the hull 2 and by detecting the displacement of the liquid level of the liquefied carbon dioxide L in the tank 10.

(6) The sixth aspect of the method S1 for adjusting pressure in a tank 10 in a ship 1 is a method S1 for adjusting pressure in a tank 10 in a ship 1 of any one of (1) to (5), and includes a step S2 of acquiring at least one of information regarding the pressure in the tank 10 and information regarding the swaying of the liquefied carbon dioxide L stored in the tank 10, and a step S4 of injecting the carbon dioxide gas G into the tank 10 using the carbon dioxide injection section 20 based on the acquired information.

This allows carbon dioxide gas G to be injected into tank 10 based on the pressure inside tank 10 and the swaying state of the liquefied carbon stored in tank 10, thereby suppressing the production of dry ice D and enabling smooth operation of tank 10.
The information regarding the pressure inside the tank 10 includes the pressure value inside the tank 10 and the temperature of the gas phase 10b inside the tank 10.
Information regarding the swaying of the liquefied carbon dioxide L stored in the tank 10 includes the detected value of acceleration caused by the swaying of the hull 2 and the detected value of the displacement of the liquid level of the liquefied carbon dioxide L in the tank 10.

1...ship 2...hull 2a...bow 3A, 3B...shipside 5...upper deck 7...superstructure 8...cargo space 10...tank 10a...liquid phase 10b...gas phase 12...cylindrical section 13...spherical end section 20...carbon dioxide injection section 21...gas tank 22...first injection pipe 22s...tip 22v...opening/closing valve 23...second injection pipe 23s...tip 23v...opening/closing 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...determination section 72...opening/closing control section 75...output section FA...bow-stern direction D...dry ice G...carbon dioxide gas L...liquefied carbon dioxide

Claims (7)

The hull and
A tank provided in the hull for storing liquefied carbon dioxide;
a high-temperature, high-pressure gas tank provided in the hull and capable of storing carbon dioxide gas having a higher temperature and pressure than the carbon dioxide in the tank;
a carbon dioxide injection unit capable of injecting high-temperature and high-pressure carbon dioxide gas stored in the high-temperature, high-pressure gas tank into the tank;
Equipped with
The carbon dioxide injection unit is
When the sway of the liquefied carbon dioxide stored in the tank reaches a predetermined level, the carbon dioxide gas is injected into the tank.
ship. The carbon dioxide injection unit is
The vessel according to claim 1 , wherein the carbon dioxide gas is injected into at least one of a gas phase and a liquid phase of carbon dioxide in the tank. The carbon dioxide injection unit is
The ship according to claim 1 or 2, wherein the carbon dioxide gas is injected into the tank when the pressure in the tank falls to or below a lower limit pressure that is set to be equal to or higher than a triple point pressure of the liquefied carbon dioxide. The design pressure of the high-temperature, high-pressure gas tank is 5 to 15.7 MPa,
The ship according to claim 1 , wherein the high-temperature, high-pressure gas tank stores the carbon dioxide gas at a temperature higher than that of the carbon dioxide in the tank and at room temperature. The hull and
A tank provided in the hull for storing liquefied carbon dioxide;
a carbon dioxide injection unit provided in the hull and capable of injecting carbon dioxide gas having a higher temperature and pressure than the carbon dioxide in the tank into the tank;
Equipped with
The carbon dioxide injection unit is
The vessel injects the carbon dioxide gas into the liquid phase of carbon dioxide in the tank. The hull and
A tank provided in the hull for storing liquefied carbon dioxide;
a carbon dioxide injection unit provided in the hull and capable of injecting carbon dioxide gas having a higher temperature and pressure than the carbon dioxide in the tank into the tank;
Equipped with
The carbon dioxide injection unit is
A ship that injects the carbon dioxide gas into the tank when the swaying of the liquefied carbon dioxide stored in the tank reaches a predetermined level. A method for regulating pressure in a tank of a ship according to any one of claims 1 to 6 , comprising:
acquiring at least one of information regarding the pressure in the tank and information regarding the swaying of the liquefied carbon dioxide stored in the tank;
and injecting the carbon dioxide gas into the tank using the carbon dioxide injection unit based on the acquired information.

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