Tank system and floating body

Abstract

This tank system comprises: a tank which is capable of storing liquefied carbon dioxide; a discharge line which is connected to the tank, which has an internal open end that opens to the inside of the tank and an external open end that opens to the outside of the tank, and which is capable of discharging the liquefied carbon dioxide from the tank to the outside of the tank; a valve which is provided partway along the discharge line and which is capable of opening and closing the flow path inside the discharge line; and a closing part which closes the external open end of the discharge line and in which is formed a through hole that has an inner diameter smaller than the inner diameter of the external open end.

Description

Tank systems, floating structures

[0001] This application claims priority to Japanese Patent Application No. 2024-092857, filed on June 7, 2024, the contents of which are incorporated herein by reference.

[0002] In ships equipped with tanks for storing liquefied gas, such as LPG (liquefied petroleum gas) ships, there are known ships that utilize the differential pressure between the pressure inside the tank and atmospheric pressure to discharge the liquefied gas outside the tank. Furthermore, ships equipped with tanks for storing liquefied gas may release the pressure inside the tank to the outside if the pressure inside the tank rises excessively. For example, Patent Document 1 discloses a configuration in which a valve opens in a discharge line (communicating pipe) that communicates with the outside of the tank when the pressure inside the tank reaches a predetermined valve operating pressure, thereby communicating the inside of the tank with the outside and discharging the pressure inside the tank to the outside.

[0003] Japanese Patent Application Laid-Open No. 2022-76210

[0004] When liquefied carbon dioxide is stored in a tank, a valve installed in the discharge line may be opened to release the liquefied carbon dioxide in the tank through the discharge line into the atmosphere outside the tank. At this time, low-temperature liquefied carbon dioxide with reduced pressure flows through the discharge line, and if the temperature of the discharge line gradually drops below the triple point temperature, the liquefied carbon dioxide flowing through the discharge line may solidify, producing dry ice in the discharge line. If dry ice is produced in the discharge line, it may lead to clogging of the discharge line, malfunction of the valve, etc.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a tank system and a float that can suppress the generation of dry ice in the discharge line and efficiently release liquefied carbon dioxide outside the tank.

[0006] In order to solve the above problems, the tank system according to the present disclosure includes a tank, a discharge line, a valve, and a closing section. The tank is capable of storing liquefied carbon dioxide. The discharge line is connected to the tank. The discharge line has an internal opening end that opens into the tank and an external opening end that opens to the outside of the tank. The discharge line is capable of discharging the liquefied carbon dioxide from the tank to the outside of the tank. The valve is provided midway along the discharge line and is capable of opening and closing a flow path within the discharge line. The closing section closes the external opening end of the discharge line and has a through hole formed therein with an inner diameter smaller than the inner diameter of the external opening end.

[0007] The tank system according to the present disclosure comprises a tank, a discharge line, a detection unit, and an adjustment valve. The tank is capable of storing liquefied carbon dioxide. The discharge line is connected to the tank. The discharge line communicates between the inside of the tank and the outside of the tank. The discharge line is capable of discharging the liquefied carbon dioxide from the tank to the outside of the tank. The detection unit detects at least one of the pressure in the discharge line, the temperature in the discharge line, and the surface temperature of the discharge line. The adjustment valve is provided midway along the discharge line. The adjustment valve is provided to be able to open and close a flow path in the discharge line, and its opening degree is adjustable.

[0008] A float according to the present disclosure comprises a float body and the above-described tank system provided on the float body.

[0009] The tank system and float disclosed herein can suppress the generation of dry ice in the discharge line and can efficiently release liquefied carbon dioxide outside the tank.

[0010] Fig. 1 is a plan view of a floating body equipped with a tank system according to an embodiment of the present disclosure. Fig. 2 is a diagram showing the configuration of a tank system according to a first embodiment of the present disclosure, and is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a diagram showing the configuration of a tank system according to a second embodiment of the present disclosure. Fig. 4 is a diagram showing the hardware configuration of a control unit according to the second embodiment of the present disclosure. Fig. 5 is a functional block diagram of a control unit according to the second embodiment of the present disclosure.

[0011] First Embodiment A tank system and a float according to an embodiment of the present disclosure will be described below with reference to Figures 1 to 5. (Configuration of Ship) As shown in Figure 1, in this embodiment, a ship 1, which is a float, transports liquefied carbon dioxide. The ship 1 includes at least a hull 2 ​​as a float main body and a tank system 10A.

[0012] (Hull Configuration) The hull 2 ​​has a pair of side walls 3A, 3B that form its outer shell, a bottom wall 4 (see Figure 2), and an upper deck 5. The side walls 3A, 3B have a pair of side wall shell plates that form the port and starboard sides, respectively. The bottom wall 4 has a bottom wall shell plate that connects the side walls 3A, 3B. The upper deck 5 illustrated in this embodiment is a full-length deck that is exposed to the outside. A superstructure 7 having accommodation areas is formed on the upper deck 5 on the stern 2b side of the hull 2. Note that the location of the superstructure 7 is merely an example, and the superstructure 7 may be located, for example, on the bow 2a side of the hull 2. A cargo carrying compartment (hold) 8 is formed within the hull 2.

[0013] (Configuration of Tank System) Figure 2 is a diagram showing the configuration of a tank system according to the first embodiment of the present disclosure, and is a cross-sectional view taken along line II-II in Figure 1. As shown in Figure 2, the tank system 10A includes at least a tank 11, a discharge line 15, a valve 20A, and a blocking unit 30. In this embodiment, two tank systems 10A are provided. Note that only one tank system 10A may be provided, or three or more tank systems 10A may be provided.

[0014] The tank 11 is capable of storing liquefied carbon dioxide L. The tank 11 is provided in the cargo carrying section 8. The tank 11 may also be provided on the upper deck 5. As shown in FIG. 2 , in this embodiment, for example, two tanks 11 are arranged at an interval in the bow-stern direction Da. The tank 11 illustrated in this embodiment has a cylindrical shape extending horizontally, but the shape of the tank 11 is not limited to a cylindrical shape and may be, for example, a spherical shape, a rectangular shape, or the like.

[0015] The discharge line 15 is connected to the tank 11. The discharge line 15 has an internal opening end 15s that opens into the tank 11 and an external opening end 15t that opens to the outside of the tank 11. The discharge line 15 communicates between the inside of the tank 11 and the outside of the tank 11. The internal opening end 15s is located at the bottom of the tank 11. The discharge line 15 is tubular and forms a flow path for liquefied carbon dioxide inside. The discharge line 15 of this embodiment has a constant flow path cross-sectional area (in other words, inner diameter), extends upward from the internal opening end 15s, penetrates the top of the tank 11 and the upper deck 5, and extends in the shape of the upper deck 5. Furthermore, the discharge line 15 of this embodiment extends above the upper deck 5 to one side in the ship's transverse direction Dw. The external opening end 15t of the discharge line opens from one ship's side 3B toward the outside in the ship's transverse direction Dw. When a valve 20A, which will be described later, is opened, the discharge line 15 can discharge the liquefied carbon dioxide from the tank 11 to the outside of the tank 11. In this embodiment, an example is shown in which the external opening end 15t is disposed above the side shell plating of the hull 2 ​​and facing outward in the horizontal direction away from the hull 2 ​​so that the discharged liquefied carbon dioxide does not come into contact with the hull 2.

[0016] The blocking section 30 blocks the external opening end 15t of the discharge line 15. A through hole 31 is formed in the blocking section 30, penetrating the blocking section 30 in the extension direction of the discharge line 15. In this embodiment, one through hole 31 is formed in the center of the blocking section 30 when the blocking section 30 is viewed from the extension direction of the discharge line 15. The inner diameter d1 of the through hole 31 is smaller than the inner diameter d2 of the external opening end 15t. The blocking section 30 having such a through hole 31 forms a so-called orifice. Note that multiple through holes 31 may be formed in the blocking section 30.

[0017] The valve 20A is provided midway along the discharge line 15. The valve 20A is configured to be able to open and close the flow path within the discharge line 15. The valve 20A in this embodiment is an on-off valve. The valve 20A is normally closed to close the flow path within the discharge line 15. The valve 20A is opened when liquefied carbon dioxide within the tank 11 is to be released to the outside of the tank 11. When the valve 20A is opened, an upstream flow path of the discharge line 15 closer to the inner opening end 15s than the valve 20A is connected to a flow path closer to the outer opening end 15t than the valve 20A. As a result, the liquefied carbon dioxide within the tank 11 passes through the discharge line 15 and is released into the atmosphere outside the ship through a through-hole 31 in a blocking portion 30 provided at the outer opening end 15t.

[0018] (Operation and Effect) The tank system 10A and the ship 1 of the above embodiment are provided with a blocking portion 30 that blocks the external opening end 15t of the discharge line 15 and has a through hole 31 formed therein with an inner diameter d1 smaller than the inner diameter d2 of the external opening end 15t. As a result, when the valve 20A is opened and liquefied carbon dioxide is discharged from the tank 11 to the outside of the tank 11 through the discharge line 15, the flow of liquefied carbon dioxide in the discharge line 15 is throttled by the through hole 31 of the blocking portion 30. This increases the pressure of the liquefied carbon dioxide in the discharge line 15, thereby suppressing a pressure drop of the liquefied carbon dioxide. Therefore, the pressure (static pressure) in the discharge line 15 can be maintained at or above the triple point, and a temperature drop of the liquefied carbon dioxide in the discharge line 15 is suppressed. Furthermore, the flow of liquefied carbon dioxide is throttled by the through hole 31, thereby increasing the flow velocity. As a result, the liquefied carbon dioxide is forcefully ejected from the discharge line 15 into the outside atmosphere. As a result, the generation of dry ice in the discharge line 15 is suppressed, and if dry ice is generated near the through hole 31, the dry ice can be blown away, thereby allowing carbon dioxide to be efficiently released outside the tank 11.

[0019] Second Embodiment Next, a second embodiment of the tank system and float according to the present disclosure will be described. In the second embodiment described below, the only difference is the configuration including a regulating valve 20B, a detection unit 40, and a control unit 60. Therefore, the same components as in the first embodiment will be denoted by the same reference numerals and will not be described again. Figure 3 is a diagram showing the configuration of a tank system according to the second embodiment of the present disclosure. As shown in Figure 3, the tank system 10B of the ship 1 according to the second embodiment includes a tank 11, a discharge line 15, a regulating valve 20B, a blocking unit 30, a detection unit 40, and a control unit 60.

[0020] The regulating valve 20B is provided in the middle of the discharge line 15. The regulating valve 20B is provided in place of the valve 20A in the first embodiment. Note that the regulating valve 20B is not limited to being provided in place of the valve 20A in the first embodiment, and for example, both the valve 20A and the regulating valve 20B may be provided in the middle of the discharge line 15. The regulating valve 20B has an adjustable opening degree, and can adjust the flow rate of liquefied carbon dioxide flowing through the flow path in the discharge line 15.

[0021] The detection unit 40 detects at least one of the pressure in the discharge line 15, the temperature in the discharge line 15, and the surface temperature of the discharge line 15. The detection unit 40 in this second embodiment is provided between the adjustment valve 20B and the external opening end 15t of the discharge line 15, and detects the pressure of the flow path in the discharge line 15. The detection unit 40 transmits the pressure detection result to the control unit 60.

[0022] 4 is a diagram showing the hardware configuration of a control unit according to a second embodiment of the present disclosure. As shown in Fig. 4, the control unit 60 has a computer including a processor 61 such as a CPU (Central Processing Unit), a ROM 62 (Read Only Memory), a RAM 63 (Random Access Memory), a storage 64 such as an HDD (Hard Disk Drive), and a signal transmission / reception module 65. The signal transmission / reception module 65 receives a detection signal from the detection unit 40.

[0023] 5 is a functional block diagram of a control unit according to a second embodiment of the present disclosure. As shown in FIG. 5, a CPU 61 of a control unit 60 executes a program stored in advance in a ROM 62, a storage 64, or the like, thereby realizing the respective functional components of a signal receiving unit 70, a valve control unit 71, and a signal output unit 72.

[0024] The signal receiving unit 70 receives the detection signal from the detecting unit 40 via the signal transmitting / receiving module 65 which is hardware.

[0025] The valve control unit 71 adjusts the aperture of the adjustment valve 20B based on the detection result of the detection unit 40. In the second embodiment, the valve control unit 71 adjusts the aperture of the adjustment valve 20B based on the detection value of the pressure in the discharge line 15 detected by the detection unit 40. The valve control unit 71 adjusts the aperture of the adjustment valve 20B so that the pressure in the discharge line 15 is equal to or greater than a preset lower limit threshold pressure and equal to or less than an upper limit threshold pressure. The aperture of the adjustment valve 20B can be obtained using a map, table, formula, or the like of the pressure in the discharge line 15 and the aperture of the adjustment valve 20B obtained in advance by simulation, experiment, or the like.

[0026] Here, the lower limit threshold for the pressure in the discharge line 15 is set so as to maintain a pressure equal to or higher than atmospheric pressure until the liquefied carbon dioxide in the discharge line 15 reaches the through-hole 31. Furthermore, the lower limit threshold for the pressure in the discharge line 15 is set, for example, to equal to or higher than the triple point of liquefied carbon dioxide. In this way, the valve control unit 71 adjusts the aperture of the adjustment valve 20B so as to maintain the pressure in the discharge line 15 equal to or higher than the triple point. Specifically, when the pressure in the discharge line 15 falls below the lower limit threshold, the valve control unit 71 increases the aperture of the adjustment valve 20B. This increases the flow rate of liquefied carbon dioxide in the discharge line 15, and the pressure in the discharge line 15 increases.

[0027] Furthermore, the upper threshold value of the pressure of the liquefied carbon dioxide in the discharge line 15 is preferably set so as to prevent a local pressure drop (static pressure drop) in the flow of liquefied carbon dioxide in the discharge line 15. The larger the aperture of the regulating valve 20B, the greater the flow rate of liquefied carbon dioxide in the discharge line 15. If the flow rate of liquefied carbon dioxide becomes excessively large, a local static pressure drop may occur in the discharge line 15, for example, upstream of the regulating valve 20B. This static pressure drop may cause vibrations due to the liquefied carbon dioxide becoming a gas-liquid two-phase flow, or dry ice formation due to a temperature drop. Therefore, the valve control unit 71 of the second embodiment adjusts the aperture value of the regulating valve 20B so that the flow rate of liquefied carbon dioxide does not become excessively large, causing a local static pressure drop in the flow of liquefied carbon dioxide. Specifically, the valve control unit 71 reduces the aperture value of the regulating valve 20B when the pressure of liquefied carbon dioxide in the discharge line 15 exceeds the upper threshold value. This reduces the flow rate of liquefied carbon dioxide in the discharge line 15, thereby suppressing the occurrence of a local drop in static pressure.

[0028] The signal output unit 72 outputs a command signal to the adjustment valve 20B to adjust the opening degree of the adjustment valve 20B to the opening degree determined by the valve control unit 71.

[0029] (Action and Effect) In the tank system 10B and the floating body 1 of the second embodiment, as in the first embodiment, when liquefied carbon dioxide is discharged from the tank 11 to the outside of the tank 11 through the discharge line 15, the flow of the liquefied carbon dioxide in the discharge line 15 is narrowed by the through-hole 31 of the blocking portion 30. This increases the pressure of the liquefied carbon dioxide in the discharge line 15, and suppresses a drop in the pressure of the liquefied carbon dioxide. Therefore, a drop in the temperature of the liquefied carbon dioxide in the discharge line 15 is suppressed, and the generation of dry ice in the discharge line 15 is suppressed. Furthermore, by narrowing the flow of the liquefied carbon dioxide by the through-hole 31, the flow rate increases. As a result, the liquefied carbon dioxide is forcefully ejected from the discharge line 15 into the outside atmosphere. As a result, the liquefied carbon dioxide can be smoothly released to the outside of the tank 11.

[0030] Furthermore, in the second embodiment, by providing the regulating valve 20B, it is possible to more appropriately adjust the opening degree of the regulating valve 20B in accordance with the pressure in the discharge line 15. This makes it possible to suppress the pressure drop of the liquefied carbon dioxide in the discharge line 15 with higher accuracy.

[0031] In addition, in the second embodiment, the control unit 60 adjusts the opening degree of the adjustment valve 20B based on the pressure in the discharge line 15, thereby reducing the burden on workers and stably suppressing the generation of dry ice in the discharge line 15.

[0032] In addition, in the second embodiment, by adjusting the opening degree of the adjustment valve 20B using the control unit 60, the liquefied carbon dioxide in the discharge line 15 can be maintained at or above the triple point pressure, and the generation of dry ice in the discharge line 15 can be stably suppressed.

[0033] (Modification of Second Embodiment) In the second embodiment, the control unit 60 is provided, but the configuration may be such that the control unit 60 is not provided. In this case, the opening degree of the adjustment valve 20B may be adjusted by an operator based on the detection result of the detection unit 40.

[0034] Furthermore, in the second embodiment described above, an example has been given in which the aperture of the regulating valve 20B is calculated based on the pressure in the discharge line 15. However, the aperture of the regulating valve 20B may be calculated based on at least one of the pressure in the discharge line 15, the temperature in the discharge line 15, and the surface temperature of the discharge line 15. For example, the control unit 60 may calculate the aperture of the regulating valve 20B by combining two or more of the pressure in the discharge line 15, the temperature in the discharge line 15, and the surface temperature of the discharge line 15, thereby further improving the accuracy of adjustment of the aperture of the regulating valve 20B.

[0035] (Other Embodiments) While the embodiments of the present disclosure have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope of the gist of the present disclosure. In each of the above embodiments, an example of the configuration of the tank systems 10A and 10B is shown, but the configuration of each part can be changed as appropriate. Similarly, in each of the above embodiments, the configuration of the hull 2 ​​is shown, but the configuration of each part of the hull 2 ​​can be changed as appropriate.

[0036] Furthermore, in each of the above embodiments, the tank systems 10A, 10B are configured to be provided on the ship 1, but the tank systems 10A, 10B may also be provided on the floating body of an offshore floating facility, a land-based liquefied gas storage facility, etc. When the tank systems 10A, 10B are provided in a land-based liquefied gas storage facility, the direction of release of the liquefied carbon dioxide released from the discharge line 15 may be directed toward the ocean, rather than toward the land side where other buildings, etc. are located. Note that the direction of release of the liquefied carbon dioxide released from the discharge line 15 is not limited to the land side, the ocean side, etc., as long as the release of the liquefied carbon dioxide does not have an impact on the surrounding area.

[0037] <Additional Notes> The tank systems 10A, 10B and the floating body 1 described in each embodiment can be understood, for example, as follows.

[0038] (1) The tank systems 10A and 10B according to the first aspect comprise a tank 11 capable of storing liquefied carbon dioxide, a discharge line 15 connected to the tank 11 and having an internal opening end 15s that opens into the tank 11 and an external opening end 15t that opens to the outside of the tank 11, and capable of discharging the liquefied carbon dioxide from the tank 11 to the outside of the tank 11, valves 20A and 20B provided midway along the discharge line 15 and capable of opening and closing a flow path within the discharge line 15, and a blocking section 30 that blocks the external opening end 15t of the discharge line 15 and has a through hole 31 formed therein, the through hole 31 having an inner diameter d1 smaller than the inner diameter d2 of the external opening end 15t.

[0039] As a result, when valves 20A and 20B are opened and liquefied carbon dioxide is discharged from tank 11 to the outside of tank 11 through discharge line 15, the flow of liquefied carbon dioxide in discharge line 15 is narrowed by through-hole 31 of blocking portion 30. Then, the pressure of liquefied carbon dioxide in discharge line 15 increases, thereby suppressing a drop in pressure of liquefied carbon dioxide. Therefore, a drop in temperature of liquefied carbon dioxide in discharge line 15 is suppressed, and the generation of dry ice in discharge line 15 is suppressed. Furthermore, the flow of liquefied carbon dioxide is narrowed by through-hole 31, thereby increasing the flow rate. As a result, liquefied carbon dioxide is forcefully ejected from discharge line 15 into the outside atmosphere. As a result, the generation of dry ice in discharge line 15 is suppressed, and if dry ice is generated near through-hole 31, the dry ice can be blown away, thereby enabling the liquefied carbon dioxide to be released smoothly to the outside of tank 11.

[0040] (2) A tank system 10B according to a second aspect is the tank system 10B of (1), in which the valve is an adjustment valve 20B whose opening degree is adjustable.

[0041] This allows the opening of the adjustment valve 20B to be adjusted according to the pressure, temperature, etc. of the liquefied carbon dioxide in the discharge line 15, and the pressure drop of the liquefied carbon dioxide can be suppressed with greater precision.

[0042] (3) The tank system 10B according to the third aspect is the tank system 10B of (2), further comprising a detection unit 40 that detects at least one of the pressure in the discharge line 15, the temperature in the discharge line 15, and the surface temperature of the discharge line 15, and a control unit 60 that adjusts the opening degree of the regulating valve 20B based on the detection result of the detection unit 40.

[0043] This reduces the burden on workers and makes it possible to easily and stably suppress the generation of dry ice in the discharge line 15.

[0044] (4) The tank system 10B according to the fourth aspect is the tank system 10B of (3), in which the control unit 60 adjusts the opening degree of the regulating valve 20B so that the liquefied carbon dioxide in the discharge line 15 is maintained at or above the triple point pressure.

[0045] As a result, by adjusting the opening degree of the adjustment valve 20B using the control unit 60, the liquefied carbon dioxide in the discharge line 15 can be maintained at or above the triple point pressure, and the generation of dry ice in the discharge line 15 can be stably suppressed.

[0046] (5) The tank system 10B according to the fifth aspect comprises a tank 11 capable of storing liquefied carbon dioxide, a discharge line 15 connected to the tank 11, communicating the inside of the tank 11 with the outside of the tank 11, and capable of discharging the liquefied carbon dioxide from the tank 11 to the outside of the tank 11, a detection unit 40 that detects at least one of the pressure in the discharge line 15, the temperature in the discharge line 15, and the surface temperature of the discharge line 15, and an adjustment valve 20B that is provided midway along the discharge line 15 and is capable of opening and closing a flow path in the discharge line 15, and has an adjustable opening.

[0047] This makes it possible to suppress the generation of dry ice in the discharge line 15 by adjusting the opening of the adjustment valve 20B based on at least one of the pressure in the discharge line 15, the temperature in the discharge line 15, and the surface temperature of the discharge line 15. As a result, the generation of dry ice in the discharge line 15 is suppressed, and the liquefied carbon dioxide can be successfully released outside the tank 11.

[0048] (6) A float 1 according to a sixth aspect comprises a float body 2 and any one of tank systems 10A, 10B according to (1) to (5) provided on the float body 2.

[0049] This configuration makes it possible to provide a float 1 equipped with tank systems 10A, 10B that can suppress the generation of dry ice in the discharge line 15 and effectively release liquefied carbon dioxide outside the tank 11. Examples of the float 1 include ships and offshore floating facilities. Examples of the float main body 2 include the hull of a ship or the float main body 2 of an offshore floating facility.

[0050] The tank system and float disclosed herein can suppress the generation of dry ice in the discharge line and can efficiently release liquefied carbon dioxide outside the tank.

[0051] REFERENCE SIGNS LIST 1 Ship (floating body) 2 Hull (floating body main body) 2a Bow 2b Stern 4 Ship bottom 5 Upper deck 7 Superstructure 8 Cargo carrying compartment (hold) 10A, 10B Tank system 11 Tank 15 Discharge line 15s Internal opening end 15t External opening end 20A Valve 20B Regulating valve (valve) 30 Blocking section 31 Through hole 40 Detection section 60 Control section 61 Processor 62 ROM 63 RAM 64 Storage 65 Signal transmitting / receiving module 70 Signal receiving section 71 Valve control section 72 Signal output section Da Bow-stern direction Dw Ship width direction L Liquefied carbon dioxide

Claims

1. A tank system comprising: a tank capable of storing liquefied carbon dioxide; a discharge line connected to the tank, having an internal opening end that opens into the tank and an external opening end that opens to the outside of the tank, and capable of discharging the liquefied carbon dioxide from the tank to the outside of the tank; a valve provided midway along the discharge line, capable of opening and closing a flow path within the discharge line; and a closing section that closes the external opening end of the discharge line and has a through hole formed therein, the through hole having an inner diameter smaller than the inner diameter of the external opening end.

2. The tank system according to claim 1, wherein the valve is an adjustable valve.

3. The tank system according to claim 2, further comprising: a detection unit that detects at least one of the pressure in the discharge line, the temperature in the discharge line, and the surface temperature of the discharge line; and a control unit that adjusts the opening of the regulating valve based on the detection results of the detection unit.

4. The tank system according to claim 3, wherein the control unit adjusts the opening of the regulating valve so that the liquefied carbon dioxide in the discharge line is maintained at or above its triple point pressure.

5. A tank system comprising: a tank capable of storing liquefied carbon dioxide; a discharge line connected to the tank, communicating the inside of the tank with the outside of the tank, and capable of discharging the liquefied carbon dioxide from the tank to the outside of the tank; a detection unit that detects at least one of the pressure in the discharge line, the temperature in the discharge line, and the surface temperature of the discharge line; and an adjustment valve that is provided midway along the discharge line and is capable of opening and closing a flow path in the discharge line, and has an adjustable opening.

6. A float comprising: a float body; and a tank system according to claim 1 or 2 provided on the float body.

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