Liquid Carbon Dioxide Storage System

Abstract

To provide a liquid carbon dioxide storage system that can continue shipment of liquid carbon dioxide without halting the shipment of liquid carbon dioxide as a whole system, even if it is estimated that carbon dioxide may solidify 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 the liquid carbon dioxide from the storage tanks, a shutoff means 600 for blocking 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 piping 150 for supplying the pressurized liquid carbon dioxide to the shipping destination, and a control unit 700 for controlling the shutoff means 600, and when solidification of the liquid carbon dioxide is predicted, the control unit 700 shuts off the discharge of liquid carbon dioxide using the shutoff means 600.

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 effects of carbon dioxide solidification and shipping carbon dioxide to CO2 transport ships, tank trucks, etc. [Background technology]

[0002] As one of the measures against global warming, a method is known in which recovered and liquefied carbon dioxide is temporarily stored in an offshore floating facility or an onshore liquefied gas storage facility, etc., and then dumped into the seabed or underground (see, for example, Patent Documents 1 to 3). For operational purposes, the recovered and liquefied carbon dioxide is temporarily stored in a plurality of storage tanks, and when the liquid carbon dioxide is shipped, the liquid carbon dioxide is shipped sequentially or simultaneously from each storage tank to a CO2 transport ship, tank truck, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4763915 [Patent Document 2] Patent No. 7245949 [Patent Document 3] Japanese Patent Publication No. 2023-183013 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes a system that liquefies unnecessary carbon dioxide and dumps it on the seabed. Rapid evaporation of liquid carbon dioxide can produce dry ice, which can clog storage tanks, piping, etc. To prevent this, the system discloses a solution in which nitrogen gas is supplied to the storage tank from the outside to maintain the pressure inside the storage tank higher than a predetermined pressure. However, this method requires the installation of a separate nitrogen supply means within the system, which contributes to the system's complexity.

[0005] Furthermore, Patent Document 2 discloses a method for estimating the state of dry ice generation in a storage tank from information on the triple point of carbon dioxide based on information on carbon dioxide impurities and its composition in order to prevent solidification of carbon dioxide in the storage tank and piping in a liquefied carbon dioxide facility, and a control method for controlling pumps and valves based on this estimation. However, there is no mention of specific solutions for ensuring the continuity of the delivery of liquefied carbon dioxide or removing dry ice after it has been generated.

[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 a shipping pump when the liquid level of the liquid carbon dioxide in the storage tank drops (remaining amount in the storage tank decreases) when shipping liquid carbon dioxide stored in a storage tank. However, when this method is adopted, the shipping amount (dispense amount) gradually decreases as the remaining amount of liquid carbon dioxide decreases, and the shipping time of the liquid carbon dioxide becomes longer.

[0007] On the other hand, if stored carbon dioxide is to be shipped to a ship or the like, it must be done within a specified time (rapid delivery and shipment are required). However, as mentioned above, if a sudden drop in pressure or temperature occurs during shipping, there is a possibility that carbon dioxide will 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 as a whole without halting the system's operation, even if there is a possibility that carbon dioxide will solidify in some storage tanks or piping. [Means for solving the problem]

[0008] In order to achieve the above object, the liquid carbon dioxide storage system of the present invention is a liquid carbon dioxide storage system including a plurality of storage tanks capable of storing liquid carbon dioxide, pipes for discharging liquid carbon dioxide from the storage tanks, shutoff means for shutting off the discharge of liquid carbon dioxide from the pipes, a liquid carbon dioxide pump for pressurizing the liquid carbon dioxide discharged from the pipes, a shipping pipe for supplying the pressurized liquid carbon dioxide to a shipping destination, and a control unit for controlling the shutoff means, wherein the control unit: Based on the pressure at the top of the storage tank and the pressure at the bottom of the storage tank, In the case where it is estimated that solidification of the liquid carbon dioxide will occur if operation is continued, Or, if it is estimated based on the pressure or temperature on the primary side of the shutoff means and the pressure or temperature on the secondary side of the shutoff means that solidification of the liquid carbon dioxide will occur if operation is continued in the shutoff means, The shutoff means is characterized in that it shuts off the discharge of liquid carbon dioxide from the storage tank.

[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] It is also preferable to introduce carbon dioxide gas, which is returned when liquid carbon dioxide is supplied to the shipping destination, into the vaporized gas supply pipe.

[0012] Furthermore, it is preferable that a pipe be 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] The control unit is also characterized in that it releases the blockage by the blocking means when it is estimated that there is no solidification of liquid carbon dioxide in the storage tank or the blocking means from which the discharge of liquid carbon dioxide has been blocked. [Effects of the Invention]

[0014] According to the liquid carbon dioxide storage system of the present invention, even if the control unit uses a shutoff means to block the discharge of liquid carbon dioxide from a storage tank where solidification is expected, shipment from other storage tanks continues, so that the shipment of liquid carbon dioxide can continue without being stopped throughout the entire system. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an example of a liquid carbon dioxide storage system according to the present invention; [Figure 2] FIG. 10 is a diagram showing the configuration of the storage tank group. [Figure 3] FIG. 1 is a phase diagram of carbon dioxide. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the liquid carbon dioxide storage system and the liquid carbon dioxide shipping method of the present invention will be described below with reference to the drawings. As a premise for the description, the possibility of solidifying carbon dioxide and saturated carbon dioxide, which are important in the technical concept of the present invention, will be described in detail below.

[0017] (Possibility of solidifying carbon dioxide) Carbon dioxide has a physical property that causes it to solidify under certain conditions, and it is possible to predict its solidification based on its triple point (0.54 MPAA, -56.6°C) and known physical properties. That is, when liquid carbon dioxide is shipped from a storage tank, for example, the solidification of carbon dioxide in the storage tank can be predicted by measuring the pressure and temperature inside the storage tank. Similarly, since liquid carbon dioxide is shipped from a storage tank through piping and valves, the solidification of carbon dioxide can be predicted by measuring the pressure and temperature inside the shipping piping and valve. In particular, when liquid carbon dioxide is decompressed through a valve, isenthalpic expansion causes a drop in temperature downstream of the valve (secondary side), which can 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 piping resistance and pressure reduction at valves. In this case, the presence of carbon dioxide gas in the piping and valves increases pressure resistance, which is expected to hinder the shipment of liquid carbon dioxide from other storage tanks. In such cases, the impact on shipments throughout the system can be minimized by temporarily stopping the shipment of liquid carbon dioxide from the storage tank in question in advance, performing a specified operation to supercool the carbon dioxide in the storage tank, and then shipping it again.

[0019] 1 is a schematic diagram showing an example of a liquid carbon dioxide storage system of the present invention. Liquid carbon dioxide storage system 1 is generally composed of carbon dioxide liquefaction equipment 100, a storage tank section 110 that stores carbon dioxide liquefied by carbon dioxide liquefaction equipment 100, a pump unit 130 that pressurizes the stored liquid carbon dioxide for shipment to a CO2 transport vessel 160, an evaporator 200, a reliquefaction device 310, and piping that connects them.

[0020] The storage tank section 110 is made up of a plurality of storage tank groups, each of which is made up of a plurality of insulated liquid carbon dioxide storage tanks. In this embodiment, the storage tank section 110 is made up of four storage tank groups 110A, 110B, 110C, and 110D. Furthermore, the storage tank group 110A is made up of four liquid carbon dioxide storage tanks 110A1, 110A2, 110A3, and 110A4. Similarly, the storage tank groups 110B and 110C are made up of four liquid carbon dioxide storage tanks. The storage tank group 110D is made up of six liquid carbon dioxide storage tanks. In other words, the storage tank section 110 in this embodiment is made up of four storage tank groups, for a total of 18 liquid carbon dioxide storage tanks.

[0021] Carbon dioxide liquefaction equipment 100 is a well-known equipment that liquefies carbon dioxide gas supplied from outside the system via piping (not shown) and carbon dioxide gas from evaporator 200 (described below). The carbon dioxide liquefied in carbon dioxide liquefaction equipment 100 is sent to each liquid carbon dioxide storage tank in storage tank section 110 via piping 105 and stored in each liquid carbon dioxide storage tank. Note that the piping connecting piping 105 to each liquid carbon dioxide storage tank is omitted in Figure 1 for ease of illustration. Furthermore, each liquid carbon dioxide storage tank in storage tank section 110 can store liquid carbon dioxide supplied from outside the system via other piping (not shown) in addition to the liquid carbon dioxide from carbon dioxide liquefaction equipment 100.

[0022] When liquid carbon dioxide is shipped from storage tank group 110A, i.e., from each liquid carbon dioxide storage tank 110A1, 110A2, 110A3, and 110A4, the liquid carbon dioxide from each storage tank is first introduced into connecting pipe 120A provided for each storage tank group. The liquid carbon dioxide is then introduced from connecting pipe 120A through common connecting pipe 140 to pump unit 130 (connecting pipe 120A and common connecting pipe 140 are connected via a valve, but are shown as connected by * in FIG. 1). In this way, the liquid carbon dioxide supplied from each storage tank group is introduced into pump unit 130 through common connecting pipe 140, where it is pressurized to a predetermined pressure. The pressurized liquid carbon dioxide is shipped to CO2 transport ship 160 via shipping pipe 150. Pump unit 130 is composed of multiple liquid carbon dioxide pumps. It is also possible to configure the liquid carbon dioxide storage tanks so that they do not form a storage tank group, and the liquid carbon dioxide is directly connected from each liquid carbon dioxide storage tank to the common connecting pipe 140.

[0023] Furthermore, a portion of the liquid carbon dioxide is extracted from the common connecting pipe 140 and introduced into the evaporator 200 for heating, whereby the liquid carbon dioxide is vaporized to form carbon dioxide gas. This carbon dioxide gas is introduced into each storage tank as needed through pipes 210 (vaporized gas supply pipes of the present invention) connected to the top of each storage tank, and is used to pressurize and heat each storage tank. In FIG. 1 , for convenience of illustration, only the pipes 210 connected to the lower storage tanks of the storage tank groups 110A, 110B, and 110C are shown, and pipes to the other storage tanks are omitted. The pipes 210 are 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 may be extracted from any location in the liquid carbon dioxide storage system 1.

[0024] Heat penetration into each storage tank may cause some of the liquid carbon dioxide stored in each storage tank to vaporize. In this case, the carbon dioxide gas at the top of the storage tank is introduced into reliquefaction device 310 via piping 300 connected to the top of each storage tank. The carbon dioxide gas introduced into reliquefaction device 310 is liquefied and can be introduced into each storage tank as liquid carbon dioxide via piping 320. In FIG. 1, for convenience of illustration, only piping 300 connected to the upper storage tanks of storage tank groups 110A, 110B, and 110C and each storage tank of storage tank group 110D is shown, and piping to other storage tanks is omitted. Furthermore, for convenience of illustration, piping connecting piping 320 to each liquid carbon dioxide storage tank is omitted in FIG. 1.

[0025] Furthermore, when liquid carbon dioxide is shipped from the liquid carbon dioxide storage system 1 to the CO2 transport ship 160, carbon dioxide gas is pushed out of the storage tank on the ship. This carbon dioxide can be recovered through piping 500 and introduced into piping 300 via piping 510, where it can be liquefied and recovered in the re-liquefaction device 310 described above. Alternatively, by introducing the carbon dioxide from piping 500 into piping 210 via piping 520, it can be combined with the carbon dioxide gas output from the evaporator 200 described above.

[0026] FIG. 2 is a diagram showing the configuration of the storage tank group 110A. Note that while FIG. 2 shows instruments and the like only for liquid carbon dioxide storage tank 110A1 as a representative example, the other storage tanks 110A2, 110A3, and 110A4 are provided with similar configurations. A valve 600 (shutoff means of the present invention) is provided in the piping connecting the bottom of liquid carbon dioxide storage tank 110A1 to connecting pipe 120A. Furthermore, an upper pressure gauge 610 that measures the pressure on the upper side of liquid carbon dioxide storage tank 110A1, a lower pressure gauge 620 that measures the pressure on the lower side of liquid carbon dioxide storage tank 110A1, and a pressure gauge 630 that measures the pressure on the secondary side (downstream side) of valve 600 are also provided. A thermometer 640 that measures the temperature on the secondary side (downstream side) of valve 600 and a thermometer 650 that measures the temperature inside liquid carbon dioxide storage tank 110A1 are also provided. A liquid level gauge 660 is installed to measure the liquid level in the liquid carbon dioxide storage tank 110A1. The various meters transmit measurement data to the control unit 700, which then controls the opening and closing of the valve 600.

[0027] The state of the liquid carbon dioxide inside the storage tank (saturated state to supercooled state) can be ascertained from the upper pressure gauge 610 and the lower pressure gauge 620, and it is possible to estimate whether solidification will occur inside the storage 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. Note that when estimating whether solidification will occur, information from the thermometer 650 and the liquid level gauge 660 may also be referenced.

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

[0029] Figure 3 is a known diagram showing the state of carbon dioxide depending on the 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, whether it is on the verge of solidifying, or whether there is a high possibility that it will solidify in the future if the current operation continues. Note that various instruments have measurement errors and time delays in data, so when estimating the state and possibility of solidification of liquid carbon dioxide inside the storage tank, it is necessary to take these errors and time delays into consideration.

[0030] For example, if the liquid carbon dioxide in the storage tank, which was in a state of point A in FIG. 3, changes to point B in FIG. 3 due to the shipping operation of the liquid carbon dioxide, if the same operation is continued, the state of the liquid carbon dioxide in the storage tank is likely to reach point C in FIG. 3. When the state of the liquid carbon dioxide in the storage tank reaches point C in FIG. 3, the carbon dioxide will solidify. Therefore, the state of the carbon dioxide in the storage tank can be grasped at predetermined time intervals, and the control unit 700 can control the opening and closing of the valve 600 so as to prevent solidification. Note that although the diagram (phase diagram) shown in FIG. 3 is used as an example of the basis and standard for estimating the state of the carbon dioxide in the storage tank, it is also possible to use other known diagrams to estimate whether solidification will occur (the possibility of solidification) or whether solidification has already occurred (the presence or absence of solidification), and further, estimation can be made using multiple different diagrams.

[0031] Liquid carbon dioxide shipped from liquid carbon dioxide storage tank 110A1 is decompressed by the amount of pressure loss through valve 600, 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 decompressed through the valve, the temperature of the liquid carbon dioxide decreases due to isentropic expansion. Therefore, it is possible to estimate the possibility of liquid carbon dioxide solidifying 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 liquid carbon dioxide will solidify in the storage tank described above.

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

[0033] If it is estimated that solidification will occur in the liquid carbon dioxide storage tank 110A1 or the valve 600 in the future, or if it is estimated that at least a portion of the liquid has already solidified, carbon dioxide gas vaporized by the evaporator 200 is introduced into the liquid carbon dioxide storage tank 110A1 via the pipe 210. The introduction of carbon dioxide gas increases the internal pressure of the tank, making it difficult for the liquid carbon dioxide in the tank to solidify. This pressurization also makes it possible to melt the partially solidified carbon dioxide.

[0034] In this embodiment, a portion of the liquid carbon dioxide in the common connecting pipe 140 before being introduced into the pump unit 130 is extracted and introduced into the evaporator 200, but it is also possible to introduce a portion of the liquid carbon dioxide in another storage tank or a portion of the liquid carbon dioxide in the shipping pipe 150 into the evaporator 200, and introduce the vaporized carbon dioxide gas into a storage tank that is expected to solidify in the future or that is expected to have at least a portion solidified.

[0035] As another method, 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 pipe 150 can be introduced into a storage tank that is estimated to solidify in the future or that is estimated to have at least partially solidified. Also, liquid carbon dioxide from the carbon dioxide liquefaction equipment 100 or the reliquefaction device 310 can be introduced into a storage tank that is estimated to solidify in the future or that is estimated to have at least partially solidified. By doing so, it is possible to raise the internal temperature of the storage tank and make the liquid carbon dioxide less likely to solidify, or to melt the 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 liquid carbon dioxide storage tank 110A1, the condition on the primary side of valve 600 is improved, and the possibility of solidification of carbon dioxide on the secondary side of valve 600 is eliminated. In addition, the possibility of solidification of carbon dioxide due to the supply of liquid carbon dioxide from the top of the storage tank is eliminated.

[0038] In this way, when liquid carbon dioxide is shipped using the liquid carbon dioxide storage system 1, even if it is estimated that there is a possibility that the liquid carbon dioxide will solidify in liquid carbon dioxide storage tank 110A, one of multiple storage tanks, by isolating only liquid carbon dioxide storage tank 110A from the system, it is possible to continue shipping liquid carbon dioxide from other storage tanks.

[0039] Furthermore, if a storage tank is suspected of solidifying in the future or has at least partially solidified and is isolated from the system, the possibility of solidification or existing solidification can be eliminated by supplying carbon dioxide gas or liquid carbon dioxide from the top of the storage tank as described above. After that, the isolation from the system can be released, and carbon dioxide can be shipped from the storage tank. This allows the system as a whole to maintain continuity in the shipment of liquid carbon dioxide.

[0040] In addition to the possibility that the liquid carbon dioxide gas in the storage tank may solidify in the future, the present invention 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 greatly, thereby achieving the effect of significantly reducing 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 shipped from the liquid carbon dioxide storage tank 110A will become a gas-liquid mixed phase state in the piping or valve 600, it is possible to temporarily block only the shipment from the liquid carbon dioxide storage tank 110A. As described above, the liquid carbon dioxide storage tank 110A can be made into a storage tank state in which no carbon dioxide gas is generated by supplying carbon dioxide gas or supplying liquid carbon dioxide from the top of the tank.

[0042] Furthermore, the present invention is not limited to the above-described exemplary embodiments, and various modifications are possible within the scope of the invention. For example, although this exemplary embodiment has a plurality of storage tank groups each consisting of a plurality of storage tanks, it is also possible to configure the system so that liquid carbon dioxide is introduced from each of the plurality of storage tanks into a connecting pipe and sent to a pump unit without using storage tank groups. It is also possible to configure the system so that a storage tank group each consisting of a plurality of storage tanks is combined with a single storage tank. The destination of this exemplary embodiment is a CO2 transport ship 160, but it may also be a trailer or the like. Furthermore, although the present invention has been described with the carbon dioxide liquefaction system 100 and the reliquefaction system 310 as separate devices, they may be a common device.

[0043] In particular, as the size of a liquid carbon dioxide storage system increases, the number of liquid carbon dioxide storage tanks that make up the system also increases. As this storage system continues to operate, the state of each liquid carbon dioxide storage tank (pressure, temperature, storage volume, etc.) will differ from tank to tank. As a result, solidification will occur at different times within each tank. However, by using the present invention, the impact of solidification on continuous shipments of liquid carbon dioxide on the entire system can be reduced. [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 to 110A4... liquid carbon dioxide storage tank, 110B1 to 110B4... liquid carbon dioxide storage tank, 110C1 to 110C4... liquid carbon dioxide storage tank, 110D1 to 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 device, 500, 510, 520...Piping, 600...Valve, 610...Upper pressure gauge, 620...Lower pressure gauge, 630...Pressure gauge, 640, 650...Thermometer, 660...Level gauge, 700...Control unit

Claims

1. a plurality of storage tanks capable of storing liquid carbon dioxide; A pipe for drawing out liquid carbon dioxide from the storage tank; a shutoff means for shutting off the discharge of liquid carbon dioxide from the piping; a liquid carbon dioxide pump that pressurizes the liquid carbon dioxide delivered from the piping; and a shipping piping that supplies the pressurized liquid carbon dioxide to a shipping destination. a control unit that controls the cutoff means; A liquid carbon dioxide storage system comprising: The control unit If it is estimated that solidification of the liquid carbon dioxide will occur in the storage tank if operation is continued based on the pressure at the top of the storage tank and the pressure at the bottom of the storage tank, or When it is estimated that solidification of the liquid carbon dioxide will occur if operation is continued in the shutoff means based on the pressure or temperature on the primary side of the shutoff means and the pressure or temperature on the secondary side of the shutoff means, A liquid carbon dioxide storage system, characterized in that the shutoff means shuts off the discharge of liquid carbon dioxide from the storage tank.

2. an evaporator for vaporizing a portion of the liquid carbon dioxide in the liquid carbon dioxide storage system; a vaporized gas supply pipe that supplies the carbon dioxide gas vaporized by the evaporator to the storage tank; 2. The liquid carbon dioxide storage system according to claim 1, further comprising:

3. 3. The liquid carbon dioxide storage system according to claim 2, wherein carbon dioxide gas that is returned when liquid carbon dioxide is supplied to the shipping destination is introduced into the vaporized gas supply pipe.

4. 2. The liquid carbon dioxide storage system according to claim 1, further comprising a pipe for supplying a portion of the liquid carbon dioxide in the liquid carbon dioxide storage system from the top of the storage tank.

5. A liquid carbon dioxide storage system as described in any one of claims 1 to 4, characterized in that the control unit releases the blockage by the blocking means when it is estimated that there is no solidification of liquid carbon dioxide in the storage tank or the blocking means from which the discharge of liquid carbon dioxide is blocked.

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