Liquid carbon dioxide storage system

Abstract

This system provides a liquid carbon dioxide storage system that can continue shipping liquid carbon dioxide without suspending shipments of the entire system, even if there is a possibility that carbon dioxide solidification may occur in some storage tanks and piping. [Solution] The liquid carbon dioxide storage system 1 comprises a plurality of carbon dioxide storage tanks 110A1 to 110D6 capable of storing liquid carbon dioxide, piping for discharging liquid carbon dioxide from the storage tanks, a shut-off means 600 for shutting off the discharge of liquid carbon dioxide from the piping, a pump unit 130 for pressurizing the liquid carbon dioxide discharged from the piping, a shipping pipe 150 for supplying the pressurized liquid carbon dioxide to the destination, and a control unit 700 for controlling the shut-off means 600. The control unit 700 shuts off the discharge of liquid carbon dioxide using the shut-off means 600 when solidification of the liquid carbon dioxide is anticipated.

Description

Technical Field

[0001] The present invention relates to a liquid carbon dioxide storage system, and more particularly to a liquid carbon dioxide storage system for suppressing the influence of carbon dioxide solidification and shipping carbon dioxide to ships for CO2 transportation, tank lorries, etc.

Background Art

[0002] As one of the measures against global warming, a method is known in which the recovered and liquefied carbon dioxide is temporarily stored in floating facilities on the ocean or liquefied gas storage facilities on land, and then injected into the seabed or underground (see, for example, Patent Documents 1 to 3). The recovered and liquefied carbon dioxide is temporarily stored in a plurality of storage tanks for operational reasons. When shipping liquid carbon dioxide, the liquid carbon dioxide is shipped from each storage tank sequentially or simultaneously to ships for CO2 transportation, tank lorries, etc.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 describes a system for liquefying unnecessary carbon dioxide and disposing of it on the seabed. Due to the rapid vaporization of liquid carbon dioxide, dry ice is generated, which may cause blockages in storage tanks, pipes, etc. To prevent this, nitrogen gas is supplied to the storage tank from the outside, and the pressure in the storage tank is maintained higher than a predetermined pressure, which is disclosed as a solution. However, in this method, it is necessary to separately provide a nitrogen supply means in the system, which contributes to the complication of the system.

[0005] Furthermore, Patent Document 2 discloses a method for estimating the dry ice formation status in a storage tank based on carbon dioxide impurity information and its composition, as well as information on the triple point of carbon dioxide, in order to prevent the solidification of carbon dioxide in the storage tank and piping of a liquefied carbon dioxide facility. It also discloses a control method for controlling pumps and valves based on this estimation. However, it does not mention specific solutions for ensuring the continuity of liquefied carbon dioxide discharge or for removing dry ice after it has been formed.

[0006] Furthermore, Patent Document 3 discloses equipment and a method for preventing solidification of carbon dioxide in a storage tank and piping by reducing the rotation speed of the shipping pump when the liquid level of liquid carbon dioxide in the storage tank drops (the remaining amount in the storage tank decreases) during the shipping of liquid carbon dioxide stored in the tank. However, if this method is adopted, the shipping amount (dispensing amount) gradually decreases as the remaining amount of liquid carbon dioxide decreases, and the shipping time for liquid carbon dioxide becomes longer.

[0007] On the other hand, when storing carbon dioxide and then shipping it to ships or other vessels, it must be done within a specified time (rapid discharge and shipping are required). However, as mentioned above, if a rapid drop in pressure and temperature occurs during shipping, carbon dioxide may solidify due to its physical properties. Therefore, the present invention aims to provide a liquid carbon dioxide storage system that can continue shipping liquid carbon dioxide without interrupting the entire system, even if there is a possibility of carbon dioxide solidification in some storage tanks and piping. [Means for solving the problem]

[0008] To achieve the above objective, the liquid carbon dioxide storage system of the present invention comprises a plurality of storage tanks capable of storing liquid carbon dioxide, piping for discharging liquid carbon dioxide from the storage tanks, shut-off means for shutting off the discharge of liquid carbon dioxide from the piping, a liquid carbon dioxide pump for pressurizing the liquid carbon dioxide discharged from the piping, shipping piping for supplying the pressurized liquid carbon dioxide to a destination, and a control unit for controlling the shut-off means, wherein the control unit, when it is estimated that solidification of the liquid carbon dioxide will occur if operation continues in the storage tank or the shut-off means, shuts off the discharge of liquid carbon dioxide from the storage tank using the shut-off means.

[0009] Furthermore, it is preferable that the control unit estimates the possibility of future solidification of liquid carbon dioxide in the storage tank based on the pressure at the top and bottom of the storage tank. In addition, if the shut-off means is a valve, it is preferable that the control unit estimates the possibility of future solidification of liquid carbon dioxide in the valve based on the pressure or temperature on the primary side of the valve and the pressure or temperature on the secondary side of the valve.

[0010] Furthermore, it is preferable to provide an evaporator that vaporizes a portion of the liquid carbon dioxide in the liquid carbon dioxide storage system, and a vaporized gas supply pipe that supplies the carbon dioxide gas vaporized by the evaporator to the storage tank.

[0011] Furthermore, it is preferable to introduce the carbon dioxide gas that returns when liquid carbon dioxide is supplied to the destination into the vaporization gas supply piping.

[0012] Furthermore, it is preferable that a pipe is provided to supply a portion of the liquid carbon dioxide in the liquid carbon dioxide storage system from the top of the storage tank.

[0013] Furthermore, the control unit is characterized in that, in the storage tank or the blocking means where the discharge of liquid carbon dioxide is blocked, if it is presumed that there is no solidification of the liquid carbon dioxide, the blocking by the blocking means is released. [Effects of the Invention]

[0014] According to the liquid carbon dioxide storage system of the present invention, even if the control unit blocks the discharge of liquid carbon dioxide from a storage tank where solidification is expected to occur using a blocking means, the discharge from other storage tanks continues, so the entire system can continue without interrupting the discharge of liquid carbon dioxide. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing one embodiment of the liquid carbon dioxide storage system of the present invention. [Figure 2] Similarly, this is a diagram showing the configuration of the storage tank group. [Figure 3] This is a phase diagram of carbon dioxide. [Modes for carrying out the invention]

[0016] The following describes one embodiment of the liquid carbon dioxide storage system and liquid carbon dioxide shipping method of the present invention with reference to the drawings. As a prerequisite to this description, the possibility of carbon dioxide solidification and saturated carbon dioxide, which are important technical concepts of the present invention, will be described in detail below.

[0017] (Potential for carbon dioxide to solidify) Carbon dioxide has the property of solidifying under certain conditions, and it is possible to predict solidification based on its triple point (0.54 MPaAA, -56.6°C) and known physical properties. In other words, when shipping liquid carbon dioxide from a storage tank, for example, solidification of the carbon dioxide in the tank can be predicted by measuring the pressure and temperature inside the tank. Similarly, since liquid carbon dioxide from a storage tank is shipped through piping and valves, solidification of the carbon dioxide can be predicted by measuring the pressure and temperature inside the shipping piping and valves. In particular, when liquid carbon dioxide is depressurized with a valve, isenthalpy expansion causes a decrease in temperature on the downstream side (secondary side) of the valve, which may lead to solidification.

[0018] (Saturated carbon dioxide) When saturated liquid carbon dioxide is shipped from a storage tank, the liquid carbon dioxide may become a gas-liquid mixed phase due to pressure reduction caused by pipeline resistance and pressure reduction in the valve. In this case, the presence of carbon dioxide gas in the pipeline and valve increases the pressure resistance, and it is predicted that the shipment of liquid carbon dioxide from other storage tanks will be inhibited. Even in such a case, it is possible to suppress the impact on the shipment of the entire system by temporarily stopping the shipment of liquid carbon dioxide from the storage tank, making the carbon dioxide in the storage tank supercooled by a predetermined operation, and then shipping it again.

[0019] FIG. 1 is a schematic configuration diagram showing an example of a form of the liquid carbon dioxide storage system of the present invention. The liquid carbon dioxide storage system 1 is schematically composed of a carbon dioxide liquefaction facility 100, a storage tank section 110 for storing the carbon dioxide liquefied by the carbon dioxide liquefaction facility 100, a pump unit 130 for boosting the pressure to ship the stored liquid carbon dioxide to a CO2 transport ship 160, an evaporator 200, a reliquefaction device 310, and pipes connecting them.

[0020] The storage tank section 110 is composed of a plurality of storage tank groups, and each storage tank group is composed of a plurality of insulated liquid carbon dioxide storage tanks. The storage tank section 110 of this exemplary form is composed of four storage tank groups 110A, 110B, 110C, and 110D. Further, the storage tank group 110A is composed of four liquid carbon dioxide storage tanks 110A1, 110A2, 110A3, and 110A4. The storage tank groups 110B and 110C are similarly composed of four liquid carbon dioxide storage tanks. The storage tank group 110D is composed of six liquid carbon dioxide storage tanks. That is, the storage tank section 110 of this exemplary form is composed of four storage tank groups and a total of 18 liquid carbon dioxide storage tanks.

[0021] The carbon dioxide liquefaction facility 100 is a well-known facility that liquefies carbon dioxide gas supplied from outside the system through piping not shown and carbon dioxide gas from an evaporator 200 described later. The liquefied carbon dioxide in the carbon dioxide liquefaction facility 100 is sent through the pipe 105 to each liquid carbon dioxide storage tank in the storage tank section 110 and stored in each liquid carbon dioxide storage tank. Regarding the pipes connecting from the pipe 105 to each liquid carbon dioxide storage tank, they are omitted in FIG. 1 due to the relationship in the drawing representation. In addition, each liquid carbon dioxide storage tank in the storage tank section 110 can also store liquid carbon dioxide supplied from outside the system through other piping not shown, in addition to the liquid carbon dioxide from the carbon dioxide liquefaction facility 100.

[0022] When shipping liquid carbon dioxide from the storage tank group 110A, that is, from each liquid carbon dioxide storage tank 110A1, 110A2, 110A3, 110A4, the liquid carbon dioxide from each storage tank is once introduced into a connecting pipe 120A provided for each storage tank group. The liquid carbon dioxide is introduced from the connecting pipe 120A into the pump unit 130 through the common connecting pipe 140 (the connecting pipe 120A and the common connecting pipe 140 are connected via a valve, but in FIG. 1, it is shown as being connected at the * part). Thus, the liquid carbon dioxide supplied from each storage tank group is introduced into the pump unit 130 through the common connecting pipe 140 and pressurized to a predetermined pressure by the pump unit 130. The pressurized liquid carbon dioxide is shipped to the CO2 transport ship 160 through the shipping pipe 150. The pump unit 130 is composed of a plurality of liquid carbon dioxide pumps. Note that the configuration may be such that the liquid carbon dioxide storage tanks do not form a storage tank group and the liquid carbon dioxide from each liquid carbon dioxide storage tank is directly connected to the common connecting pipe 140.

[0023] Furthermore, by extracting a portion of the liquid carbon dioxide from the common connecting pipe 140 and introducing it into the evaporator 200 for heating, the liquid carbon dioxide is vaporized and converted into carbon dioxide gas. This carbon dioxide gas is then introduced into each storage tank via piping 210 (the vaporization gas supply piping of the present invention), which is connected to the top of each storage tank, as needed, and is used to pressurize and heat each storage tank. In Figure 1, for the sake of illustrative representation, only the piping 210 that introduces the heated and vaporized carbon dioxide gas from the evaporator 200 to each storage tank is shown, and the piping to the lower storage tanks of the storage tank groups 110A, 110B, and 110C is shown, while the piping to the other storage tanks is omitted. Piping 210 is further connected to the carbon dioxide liquefaction equipment 100. Note that the liquid carbon dioxide introduced into the evaporator 200 is not limited to the liquid carbon dioxide in the common connecting pipe 140, but can be extracted from any point in the liquid carbon dioxide storage system 1.

[0024] Due to heat intrusion into each storage tank, some of the liquid carbon dioxide stored in each tank may vaporize. In this case, the carbon dioxide gas at the top of the storage tank is introduced into the reliquefaction unit 310 via piping 300 connected to the top of each storage tank. The carbon dioxide gas introduced into the reliquefaction unit 310 is liquefied and can be introduced into each storage tank as liquid carbon dioxide via piping 320. In Figure 1, for the sake of illustrative representation, only the piping 300 connected to the upper storage tanks of storage tank groups 110A, 110B, and 110C and to each storage tank of storage tank group 110D is shown, and the piping to the other storage tanks is omitted. Also, the piping connecting piping 320 to each liquid carbon dioxide storage tank is omitted in Figure 1 for the sake of illustrative representation.

[0025] Furthermore, when liquid carbon dioxide is shipped from the liquid carbon dioxide storage system 1 to the CO2 transport vessel 160, carbon dioxide gas is pushed out of the storage tanks on the vessel. This carbon dioxide can be recovered in the piping 500 and introduced into the piping 300 via piping 510, allowing it to be liquefied and recovered in the aforementioned reliquefaction device 310. Alternatively, it can be introduced from piping 500 into piping 210 via piping 520, allowing it to be combined with the carbon dioxide gas discharged from the aforementioned evaporator 200.

[0026] Figure 2 shows the configuration of the storage tank group 110A. In Figure 2, the instruments and other equipment are shown only for the liquid carbon dioxide storage tank 110A1 as a representative example, but the other storage tanks 110A2, 110A3, and 110A4 have a similar configuration. A valve 600 (the shut-off means of the present invention) is provided in the piping that connects the bottom of the liquid carbon dioxide storage tank 110A1 to the connecting pipe 120A. Furthermore, an upper pressure gauge 610 for measuring the pressure on the upper side of the liquid carbon dioxide storage tank 110A1, a lower pressure gauge 620 for measuring the pressure on the lower side of the liquid carbon dioxide storage tank 110A1, and a pressure gauge 630 for measuring the pressure on the secondary side (downstream side) of the valve 600 are installed. In addition, a thermometer 640 for measuring the temperature on the secondary side (downstream side) of the valve 600 and a thermometer 650 for measuring the temperature inside the liquid carbon dioxide storage tank 110A1 are installed. A liquid level gauge 660 is installed to measure the liquid level in the liquid carbon dioxide storage tank 110A1. The various instruments then transmit measurement data to the control unit 700, which controls the opening and closing of the valve 600.

[0027] The upper pressure gauge 610 and lower pressure gauge 620 allow us to understand the state of the liquid carbon dioxide inside the storage tank (saturated to supercooled), and estimate whether solidification will occur inside the tank in the future. At the top of the storage tank, the liquid carbon dioxide is saturated, and the temperature can be estimated from the pressure. In addition, information from the thermometer 650 and liquid level gauge 660 may also be referred to when estimating whether solidification will occur.

[0028] Whether solidification has already occurred on the secondary (downstream) side of valve 600 (presence or absence of solidification) can be estimated from the pressure or temperature on the primary and secondary sides of valve 600, respectively. The lower pressure gauge 620 and thermometer 650 can be used to measure the primary pressure and temperature of valve 600. Additionally, the pressure gauge 630 or a pressure gauge (not shown) installed on the suction side of the pump unit 130 located downstream of the valve can be used to measure the secondary pressure of valve 600.

[0029] Figure 3 is a well-known diagram showing the state of carbon dioxide under temperature and pressure. By comparing data from various instruments with Figure 3, it is possible to estimate whether the liquid carbon dioxide inside the storage tank has already solidified, is on the verge of solidifying, or is likely to solidify in the future if current operation continues. However, since various instruments have measurement errors and time delays in their data, these errors and time delays must be taken into account when estimating the state and possibility of solidification of liquid carbon dioxide inside the storage tank.

[0030] For example, if the liquid carbon dioxide in the storage tank, which was in the state shown at point A in Figure 3, changes to point B in Figure 3 due to the liquid carbon dioxide discharge operation, continuing the same operation will likely result in the state of the liquid carbon dioxide in the storage tank becoming point C in Figure 3. When the state of the liquid carbon dioxide in the storage tank becomes point C in Figure 3, the carbon dioxide will solidify. Therefore, the state of the carbon dioxide in the storage tank can be monitored at predetermined intervals, and the control unit 700 can control the opening and closing of the valve 600 to prevent solidification. Although the diagram (state diagram) shown in Figure 3 was used as an example of the basis / criteria for estimating the state of the carbon dioxide in the storage tank, it is also possible to estimate whether solidification will occur (possibility of solidification, whether solidification has already occurred (presence or absence of solidification)) using other known diagrams, and furthermore, it is possible to estimate using multiple different diagrams.

[0031] The liquid carbon dioxide being released from the liquid carbon dioxide storage tank 110A1 is depressurized by valve 600 to reduce pressure loss, introduced into connecting pipe 120A, and further introduced into pump unit 130 via common connecting pipe 140, where it is pressurized. When the liquid carbon dioxide is depressurized by the valve, the temperature of the liquid carbon dioxide decreases due to isentropic expansion. Therefore, it is possible to estimate the possibility of solidification of the liquid carbon dioxide on the secondary side of valve 600 from the temperature (thermometer 650) and pressure (lower pressure gauge 620) on the primary side (upstream side) of valve 600, and the temperature (thermometer 640) and pressure (pressure gauge 630) on the secondary side (downstream side). Specifically, this can be estimated in the same way as the estimation of whether solidification of liquid carbon dioxide occurs in the storage tank described above.

[0032] As described above, if it is estimated that solidification of liquid carbon dioxide will occur inside the storage tank in the future, or if it is estimated that solidification of liquid carbon dioxide will occur on the secondary side of valve 600 in the future, the control unit 700 will close valve 600. This prevents solidification of liquid carbon dioxide inside the storage tank and valve, and also prevents solidified carbon dioxide from mixing into the connecting pipe 120A and pump unit 130. Furthermore, if it is estimated that there is no longer a possibility of solidification of liquid carbon dioxide inside the storage tank, the control unit 700 will open valve 600.

[0033] If solidification is anticipated to occur in the liquid carbon dioxide storage tank 110A1 or valve 600 in the future, or if at least a portion of it has already solidified, carbon dioxide gas vaporized by the evaporator 200 is introduced into the liquid carbon dioxide storage tank 110A1 via piping 210. The introduction of carbon dioxide gas increases the internal pressure of the storage tank, making it less likely for the liquid carbon dioxide inside the tank to solidify. Furthermore, this pressurization can melt any partially solidified carbon dioxide.

[0034] In this example, a portion of the liquid carbon dioxide in the common connecting pipe 140 is extracted before being introduced into the pump unit 130 and introduced into the evaporator 200. However, it is also possible to introduce a portion of the liquid carbon dioxide in other storage tanks or a portion of the liquid carbon dioxide in the shipping piping 150 into the evaporator 200, and then introduce the vaporized carbon dioxide gas into storage tanks where solidification is expected to occur in the future, or where at least a portion has already solidified.

[0035] Alternatively, a portion of the liquid carbon dioxide in another storage tank, a portion of the liquid carbon dioxide in the common connecting pipe 140, or a portion of the liquid carbon dioxide in the shipping piping 150 can be introduced into a storage tank where solidification is anticipated in the future, or where at least a portion has already solidified. Furthermore, liquid carbon dioxide from the carbon dioxide liquefaction equipment 100 or the reliquefaction unit 310 can also be introduced into a storage tank where solidification is anticipated in the future, or where at least a portion has already solidified. These methods can raise the internal temperature of the storage tank, making it less likely for the liquid carbon dioxide to solidify, or they can melt any partially solidified carbon dioxide.

[0036] In this case, by introducing liquid carbon dioxide from the top of the storage tank, the solidified carbon dioxide can be efficiently melted.

[0037] In this way, by increasing the pressure and temperature inside the liquid carbon dioxide storage tank 110A1, the condition on the primary side of valve 600 is improved, eliminating the possibility of carbon dioxide solidification on the secondary side of valve 600. Furthermore, the supply of liquid carbon dioxide from the top of the storage tank eliminates the possibility of carbon dioxide solidification.

[0038] Thus, when shipping liquid carbon dioxide using the liquid carbon dioxide storage system 1, even if it is estimated that solidification may occur in the liquid carbon dioxide storage tank 110A, which is one of the multiple storage tanks, by isolating only the liquid carbon dioxide storage tank 110A from the system, it is possible to continue shipping liquid carbon dioxide from the other storage tanks.

[0039] Furthermore, if solidification is anticipated to occur in the future, or if at least a portion has already solidified, and the storage tank is isolated from the system, the possibility of solidification or any existing solidification can be eliminated by supplying carbon dioxide gas as described above, or by supplying liquid carbon dioxide from the top of the storage tank. After that, the isolation from the system can be released, and end-of-carbon dioxide can be shipped from the storage tank. This allows the continuity of liquid carbon dioxide shipments to be maintained for the entire system.

[0040] This invention addresses the possibility of liquid carbon dioxide gas solidifying in the storage tank in the future, and also focuses on the secondary side of the shut-off means (valve) in the liquid carbon dioxide shipping system, where the physical state of the liquid carbon dioxide changes relatively significantly. This allows for a significant reduction in the impact on continuous shipping caused by the solidification of liquid carbon dioxide gas.

[0041] Furthermore, even if there is a possibility that the liquid carbon dioxide being discharged from the liquid carbon dioxide storage tank 110A may become a gas-liquid mixed-phase state within the piping or valve 600, the discharge from the liquid carbon dioxide storage tank 110A can be temporarily shut off. As described above, the liquid carbon dioxide storage tank 110A can be kept in a state where no carbon dioxide gas is generated by supplying carbon dioxide gas or supplying liquid carbon dioxide from the top of the storage tank.

[0042] Furthermore, the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the invention. For example, although this embodiment includes multiple storage tank groups consisting of multiple storage tanks, it is also possible to configure the system without storage tank groups, by introducing liquid carbon dioxide from each of the multiple storage tanks into connecting pipes and sending it to a pump unit. Alternatively, it is possible to configure the system using a combination of storage tank groups consisting of multiple storage tanks and a single storage tank. In this embodiment, the destination is a CO2 transport vessel 160, but it may also be a trailer or the like. In addition, although the carbon dioxide liquefaction equipment 100 and the reliquefaction equipment 310 have been described as separate devices in the present invention, they may be used as a common device.

[0043] In particular, as liquid carbon dioxide storage systems become larger, the number of liquid carbon dioxide storage tanks that make up the system increases. If this storage system continues to operate, the conditions of each liquid carbon dioxide storage tank (pressure, temperature, storage volume, etc.) will differ from tank to tank. As a result, the timing of solidification occurring inside each tank will vary. However, by using the present invention, it is possible to reduce the impact of solidification on the continuous shipment of liquid carbon dioxide for the entire system. [Explanation of Symbols]

[0044] 1…Liquid carbon dioxide storage system, 100…Carbon dioxide liquefaction equipment, 105…Piping, 110…Storage tank section, 110A, 110B, 110C, 110D…Storage tank group, 110A1~110A4…Liquid carbon dioxide storage tank, 110B1~110B4…Liquid carbon dioxide storage tank, 110C1~110C4…Liquid carbon dioxide storage tank, 110D1~110D6…Liquid carbon dioxide storage tank, 120A ...connecting pipe, 130...pump unit, 140...common connecting pipe, 150...shipping piping, 160...CO2 transport vessel, 200...evaporator, 210...piping, 300, 320...piping, 310...reliquefaction equipment, 500, 510, 520...piping, 600...valve, 610...upper pressure gauge, 620...lower pressure gauge, 630...pressure gauge, 640, 650...thermometer, 660...liquid level gauge, 700...control unit

Claims

1. Multiple storage tanks capable of storing liquid carbon dioxide, A pipe for discharging liquid carbon dioxide from the aforementioned storage tank, A blocking means for blocking the discharge of liquid carbon dioxide from the aforementioned piping, A liquid carbon dioxide pump for pressurizing the liquid carbon dioxide discharged from the aforementioned piping, and shipping piping for supplying the pressurized liquid carbon dioxide to the destination, A control unit that controls the blocking means, In a liquid carbon dioxide storage system equipped with, A liquid carbon dioxide storage system characterized in that, when the control unit estimates that solidification of the liquid carbon dioxide will occur if operation continues in the storage tank or the shut-off means, the shut-off means shuts off the discharge of liquid carbon dioxide from the storage tank.

2. The liquid carbon dioxide storage system according to claim 1, characterized in that the control unit estimates the possibility of future solidification of liquid carbon dioxide in the storage tank based on the pressure at the top of the storage tank and the pressure at the bottom of the storage tank.

3. The aforementioned shut-off means is a valve, The liquid carbon dioxide storage system according to claim 1, characterized in that the control unit estimates the possibility of future solidification of liquid carbon dioxide in the valve based on the pressure or temperature on the primary side of the valve and the pressure or temperature on the secondary side of the valve.

4. An evaporator that vaporizes a portion of the liquid carbon dioxide in the aforementioned liquid carbon dioxide storage system, A vaporization gas supply pipe supplies the carbon dioxide gas vaporized by the evaporator to the storage tank. A liquid carbon dioxide storage system according to claim 1, characterized by the provision of a feature.

5. The liquid carbon dioxide storage system according to claim 4, characterized in that the carbon dioxide gas that returns when liquid carbon dioxide is supplied to the aforementioned destination is introduced into the vaporization gas supply piping.

6. The liquid carbon dioxide storage system according to claim 1, characterized in that a pipe is provided for supplying a portion of the liquid carbon dioxide in the liquid carbon dioxide storage system from the top of the storage tank.

7. The liquid carbon dioxide storage system according to any one of claims 1 to 6, characterized in that the control unit releases the blockage by the blockage means when it is presumed that there is no solidification of the liquid carbon dioxide in the storage tank or the blockage means that has blocked the discharge of the liquid carbon dioxide.

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