Liquefied carbon dioxide equipment, ships, and control methods for liquefied carbon dioxide equipment

Abstract

By accurately monitoring the dry ice formation process, we can more effectively suppress dry ice production. [Solution] The liquefied carbon dioxide equipment comprises a tank, a piping section, a pressure detection sensor for detecting the pressure value in the system where liquefied carbon dioxide is present, a pressurizing section, and a control device. The control device includes a triple point pressure determination section that determines whether the pressure value detected by the pressure detection sensor is below the triple point pressure of carbon dioxide, a dry ice generation condition determination section that determines whether the change in the pressure value detected by the pressure detection sensor satisfies predetermined dry ice generation conditions when the dry ice generation condition determination section determines that the dry ice generation conditions are met, and a pressurizing control section that pressurizes the system using the pressurizing section.

Description

Technical Field

[0001] The present disclosure relates to a liquefied carbon dioxide facility, a ship, and a method for controlling a liquefied carbon dioxide facility.

Background Art

[0002] In a tank that stores liquefied carbon dioxide or in a pipe through which liquefied carbon dioxide flows, when the pressure of the liquefied carbon dioxide decreases, the liquefied carbon dioxide may freeze and dry ice may be generated. When dry ice is generated, the flow of liquefied carbon dioxide in the pipe may be inhibited. Therefore, in a liquefied carbon dioxide facility including a tank for storing liquefied carbon dioxide and a pipe, it is necessary to suppress the generation of dry ice.

[0003] For example, Patent Document 1 discloses a configuration including a pressure sensor, a temperature sensor, and an estimation unit. In this configuration, the pressure sensor detects the pressure in the region where liquefied carbon dioxide exists. The temperature sensor detects the temperature in the region where liquefied carbon dioxide exists. The estimation unit estimates the generation status of dry ice in the region where liquefied carbon dioxide exists based on the detection results of the pressure sensor and the temperature sensor.

[0004] However, the generation status of dry ice can also vary depending on the degree of impurities contained in the liquefied carbon dioxide. Therefore, even if the generation status of dry ice is estimated based on the pressure and temperature in the region where liquefied carbon dioxide exists, it may differ from the actual dry ice generation status. Thus, in the configuration described in Patent Document 1, information on the triple point based on the composition of the liquid containing liquefied carbon dioxide and the impurities mixed in the liquefied carbon dioxide is stored, and the detection results of the pressure sensor and the temperature sensor are compared with the information on the triple point corresponding to the amount of the stored impurities to estimate the generation status of dry ice.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Patent No. 7245949 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, even with the configuration described in Patent Document 1, the dry ice formation status is only estimated, and there is a possibility of discrepancies between this estimate and the actual dry ice formation status. Therefore, it is desirable to grasp the dry ice formation status with high accuracy and suppress dry ice formation more effectively.

[0007] This disclosure was made to solve the above-mentioned problems and aims to provide a liquefied carbon dioxide facility, a ship, and a control method for a liquefied carbon dioxide facility that can accurately grasp the dry ice generation status and more effectively suppress dry ice generation. [Means for solving the problem]

[0008] To solve the above problems, the liquefied carbon dioxide equipment according to this disclosure comprises a tank, a piping section, a pressure detection sensor, a pressurizing section, and a control device. The tank is capable of storing liquefied carbon dioxide. The piping section is connected to the tank and through which the liquefied carbon dioxide can flow. The pressure detection sensor detects the pressure value in the system where the liquefied carbon dioxide is present, inside at least one of the tank and the piping section. The pressurizing section can pressurize the system. The control device controls the pressurizing section. The control device includes a triple point pressure determination unit, a dry ice generation condition determination unit, and a pressurizing control unit. The triple point pressure determination unit determines whether the pressure value detected by the pressure detection sensor is less than or equal to the triple point pressure of carbon dioxide. The dry ice generation condition determination unit determines whether, given that the triple point pressure determination unit has determined that the pressure value is less than or equal to the triple point pressure of carbon dioxide, the change in the pressure value detected by the pressure detection sensor satisfies predetermined dry ice generation conditions. The pressurization control unit pressurizes the system using the pressurization unit when the dry ice generation condition determination unit determines that the dry ice generation conditions are met.

[0009] The vessel relating to this disclosure comprises a hull and the liquefied carbon dioxide equipment described above.

[0010] The control method for a liquefied carbon dioxide facility according to this disclosure is a control method for a liquefied carbon dioxide facility comprising a tank, a piping section, a pressure detection sensor, and a pressurizing section. The tank is capable of storing liquefied carbon dioxide. The piping section is connected to the tank and through which the liquefied carbon dioxide can flow. The pressure detection sensor detects the pressure value in a system containing the liquefied carbon dioxide inside at least one of the tank and the piping section. The pressurizing section can pressurize the system. The control method for the liquefied carbon dioxide facility includes the steps of: determining whether the pressure value is less than or equal to the triple point pressure of carbon dioxide; determining whether the dry ice generation conditions have been met; and pressurizing the system. In the step of determining whether the pressure value is less than or equal to the triple point pressure of carbon dioxide, it is determined whether the pressure value detected by the pressure detection sensor is less than or equal to the triple point pressure of carbon dioxide. In the step of determining whether the dry ice generation conditions have been met, it is determined whether the pressure value has met predetermined dry ice generation conditions, given that it has been determined that the pressure value is less than or equal to the triple point pressure of carbon dioxide. In the step of pressurizing the system, if it is determined that the dry ice generation conditions are met, the pressurizing unit pressurizes the system. [Effects of the Invention]

[0011] According to the liquefied carbon dioxide equipment, vessel, and control method for the liquefied carbon dioxide equipment described herein, the dry ice generation status can be grasped with high accuracy, and the generation of dry ice can be suppressed more effectively. [Brief explanation of the drawing]

[0012] [Figure 1] This is a plan view of a vessel according to an embodiment of the present disclosure. [Figure 2] This figure shows the configuration of a liquefied carbon dioxide facility according to the first embodiment of this disclosure. [Figure 3] This figure shows the hardware configuration of a control device according to an embodiment of the present disclosure. [Figure 4] This is a functional block diagram of a control device according to an embodiment of the present disclosure. [Figure 5] This figure shows an example of the pressure changes that occur when dry ice is produced. [Figure 6] This flowchart shows the procedure for a control method of a liquefied carbon dioxide facility according to an embodiment of the present disclosure. [Figure 7] This figure shows the state of pressurization being performed by the pressurizing unit in the liquefied carbon dioxide facility shown in Figure 2. [Figure 8] This figure shows an example of the changes in pressure and temperature of liquefied carbon dioxide when pressurized by the pressurizing unit, and when not pressurized by the pressurizing unit. [Figure 9] This figure shows the configuration of a liquefied carbon dioxide facility according to the second embodiment of this disclosure. [Figure 10] This figure shows the state of pressurization being performed by the pressurizing unit in the liquefied carbon dioxide facility shown in Figure 9. [Figure 11] This figure shows the state in which the liquid supply unit is supplying liquid in the liquefied carbon dioxide facility shown in Figure 9. [Modes for carrying out the invention]

[0013] <First Embodiment> Hereinafter, the liquefied carbon dioxide equipment, vessel, and control method for the liquefied carbon dioxide equipment according to the embodiments of this disclosure will be described with reference to Figures 1 to 11. (Ship composition) As shown in Figure 1, the vessel 1 of the embodiment of this disclosure mainly comprises a hull 2 ​​and a liquefied carbon dioxide equipment 10A.

[0014] (Hull structure) The hull 2 ​​has a pair of side panels 3A and 3B that form its outer shell, a bottom (not shown), and an upper deck 5. The side panels 3A and 3B each have a pair of side platings that form the port and starboard sides, respectively. The bottom (not shown) has bottom platings that connect these side panels 3A and 3B. The upper deck 5 is a full-length deck that is exposed to the outside. The hull 2 ​​has a superstructure 7 with living quarters formed on the upper deck 5 on the stern 2b side, for example.

[0015] In the hull 2 of the present embodiment, a carbon dioxide storage compartment (hold) 8 is formed on the bow 2a side of the superstructure 7. Note that the arrangement of the carbon dioxide storage compartment 8 is an example, and the carbon dioxide storage compartment 8 may be arranged, for example, on the stern 2b side of the superstructure 7 or the like.

[0016] (Configuration of the liquefied carbon dioxide facility) FIG. 2 is a diagram showing the configuration of a liquefied carbon dioxide facility according to the first embodiment of the present disclosure. As shown in FIG. 2, the liquefied carbon dioxide facility 10A includes a tank 11, a piping section 100, a pressure detection sensor 21, a temperature detection sensor 22, a pressurizing section 40A, a control device 60, and an information output section 80.

[0017] As shown in FIG. 1, the tank 11 is provided in the hull 2. The tank 11 of the present embodiment is provided in the carbon dioxide storage compartment 8 and is arranged in a plurality along the fore-and-aft direction FA. The tank 11 may be provided above the upper deck 5. The case where two tanks 11 are arranged at intervals in the fore-and-aft direction FA is illustrated in the present embodiment. The tanks 11 may be arranged side by side in the ship width direction, for example. The tank 11 of the present embodiment has a cylindrical shape extending in the horizontal direction. Note that the tank 11 is not limited to a cylindrical shape, and the tank 11 may be spherical, square, or the like. Also, the number of installations, arrangements, etc. of the tank 11 can be changed as appropriate.

[0018] As shown in FIG. 2, the tank 11 can store liquefied carbon dioxide. A liquid phase and a gas phase are formed in the tank 11. The liquid phase, that is, liquefied carbon dioxide which is carbon dioxide in a liquid state, is stored in the lower part of the tank 11. The gas phase is stored in the upper part of the tank 11. The gas phase contains carbon dioxide in a gaseous state. As the carbon dioxide in a gaseous state, boil-off gas generated by natural vaporization of liquefied carbon dioxide in the tank 11 due to heat input from the outside can be exemplified.

[0019] The piping section 100 is connected to the tank 11 and is capable of circulating at least liquefied carbon dioxide. In this embodiment, the piping section 100 includes a loading line 13 and a discharge line 14. The loading line 13 and the discharge line 14 can be connected to offshore storage facilities (not shown) via a connecting line 18. An on / off valve 18v is provided in the middle of the connecting line 18.

[0020] The loading line 13 is configured to load liquefied carbon dioxide supplied from offshore storage facilities, etc., into the tank 11 via a connecting line 18. In this embodiment, the loading line 13 branches into an upper loading line 13A and a lower loading line 13B midway.

[0021] The upper loading line 13A extends downward through the inside of the tank 11, for example, from outside the tank 11, through the top of the tank 11. An on / off valve 13v is provided along the upper loading line 13A. In this embodiment, the tip 13s of the upper loading line 13A is located in the upper part of the tank 11. The upper loading line 13A releases liquefied carbon dioxide supplied to the tank 11 from its tip 13s into the upper part of the tank 11. The tip 13s of the upper loading line 13A is usually located in the upper gas phase of the tank 11 and is capable of releasing liquefied carbon dioxide into the gas phase.

[0022] The lower loading line 13B extends from outside the tank 11, for example, through the top of the tank 11, and downward through the inside of the tank 11. An on / off valve 13w is provided along the lower loading line 13B. The tip 13t of the lower loading line 13B is located in the lower part of the inside of the tank 11. The tip 13t of the lower loading line 13B is located in the lower liquid phase inside the tank 11. The lower loading line 13B releases the liquefied carbon dioxide supplied to the tank 11 from its tip 13t into the lower part of the tank 11.

[0023] The discharge line 14 is capable of discharging liquefied carbon dioxide from the tank 11 to the outside of the ship through the connecting line 18. At least a portion of the discharge line 14 extends from outside the tank 11, for example, through the top of the tank 11, and through the inside of the tank 11 towards the bottom. An on / off valve 14v is provided in the middle of the discharge line 14. The discharge line 14 in this embodiment is equipped with a load pump 15. The load pump 15 is capable of pumping liquefied carbon dioxide from the tank 11. The discharge line 14 discharges the liquefied carbon dioxide pumped from the load pump 15 to the outside of the tank 11 (outside the ship) through the connecting line 18.

[0024] In this embodiment, the area enclosed by the on-off valve 13v of the upper loading line 13A, the on-off valve 13w of the lower loading line 13B, the on-off valve 14v of the discharge line 14, and the on-off valve 18v of the connection line 18 within the piping section 100 described above is set as system K. Note that the area set as system K may be an area other than those described above. For example, system K may be set in another part of the piping section 100, or it may be set inside the tank 11. Furthermore, system K may be set across the piping section 100 and the tank 11.

[0025] The pressure detection sensor 21 detects the pressure value of K within the system. The pressure detection sensor 21 is installed, for example, in the discharge line 14. The temperature detection sensor 22 detects the temperature value of K within the system. The temperature detection sensor 22 is installed, for example, in the discharge line 14. Note that the installation location of the pressure detection sensor 21 may be any other suitable location as long as it can detect the pressure value of K within the system. Similarly, the installation location of the temperature detection sensor 22 may be any other suitable location as long as it can detect the temperature value of K within the system.

[0026] The pressurizing unit 40A is configured to pressurize the system K. In this embodiment, the pressurizing unit 40A pressurizes the system K by supplying carbon dioxide gas at a higher pressure than the system K from an external pressure source to the system K. An example of an external pressure source is another tank 11 provided inside the hull 2. The pressurizing unit 40A includes a pressurizing line 41 and a ventilation line 42.

[0027] The pressurizing line 41 is connected to an external pressure supply source. A shut-off valve 41v is provided in the middle of the pressurizing line 41. The pressurizing unit 40A opens the shut-off valve 41v to supply carbon dioxide gas from another tank 11, which is an external pressure supply source, to the system K through the pressurizing line 41. The pressurizing unit 40A may also be equipped with a pump or compressor (not shown) to increase the pressure of the carbon dioxide gas supplied to the system K through the pressurizing line 41. The pressurizing unit 40A supplies carbon dioxide gas at a higher pressure to the system K, causing the pressure in the system K to rise.

[0028] One end of the ventilation line 42 is connected to the piping section 100 of the system K. The other end of the ventilation line 42 is connected to an external pressure supply source. The other end of the ventilation line 42 may also be connected to the gas phase of another tank 11, for example. An on-off valve 42v is provided in the middle of the ventilation line 42. When the ventilation line 42 supplies carbon dioxide gas to the system K through the pressurization line 41, it opens the on-off valve 42v to circulate the liquefied carbon dioxide pushed out of the system K to the external pressure supply source.

[0029] Furthermore, the pressurizing unit 40A may supply carbon dioxide gas at a higher temperature than the system temperature K from an external pressure source to the system temperature K. In this case, the pressurizing unit 40A may supply room temperature carbon dioxide gas at a higher temperature than the system temperature K from an external pressure source to the system temperature K. To supply carbon dioxide gas at a higher temperature than the system temperature K, for example, carbon dioxide gas supplied from another tank 11 may be heated by a heater (not shown) installed in the pressurizing line 41.

[0030] (Hardware configuration diagram) Figure 3 is a diagram showing the hardware configuration of a control device according to the embodiment of this disclosure. As shown in Figure 3, the control device 60 illustrated in this embodiment is a computer equipped with a CPU 61 (Central Processing Unit), ROM 62 (Read Only Memory), RAM 63 (Random Access Memory), storage 64, and a communication module 65.

[0031] (Functional block diagram) Figure 4 is a functional block diagram of a control device according to an embodiment of this disclosure. As shown in Figure 4, the CPU 61 of the control device 60 executes programs stored in the ROM 62, storage 64, etc., to realize the functional configurations of the signal input unit 70, the triple point pressure determination unit 72, the dry ice generation condition determination unit 73, the pressurization control unit 74, and the output unit 75.

[0032] The signal input unit 70 receives detection signals from the pressure detection sensor 21 and the temperature detection sensor 22 via the communication module 65.

[0033] The triple point pressure determination unit 72 monitors the pressure and temperature values ​​of the system K based on detection signals from the pressure detection sensor 21 and temperature detection sensor 22 received by the signal input unit 70. The triple point pressure determination unit 72 determines whether the pressure value detected by the pressure detection sensor 21 is less than or equal to the triple point pressure of carbon dioxide.

[0034] The dry ice generation condition determination unit 73 determines whether or not dry ice is being generated in system K based on the pressure value in system K. The dry ice generation condition determination unit 73 determines whether or not the change in the pressure value detected by the pressure detection sensor 21 satisfies the predetermined dry ice generation conditions, given that the triple point pressure determination unit 72 has determined that the pressure value in system K is less than or equal to the triple point pressure of carbon dioxide.

[0035] Figure 5 shows an example of the pressure change that occurs when dry ice is produced. As shown in Figure 5, for example, if a pressure drop occurs in the system K due to a leak or the like, liquefied carbon dioxide will remain in a liquid state even if the pressure continues to drop after falling below the triple point pressure (state A1) (states A1-A2 in Figure 5). Subsequently, when liquefied carbon dioxide begins to turn from a liquid state into dry ice, the pressure rapidly increases (recovers) to near the triple point pressure (states A2-A3 in Figure 5). After that, liquefied carbon dioxide maintains a mixed state of gas, liquid, and dry ice before completely turning into dry ice.

[0036] The dry ice generation conditions used for determination by the dry ice generation condition determination unit 73 are preset based on the change in pressure value when liquefied carbon dioxide turns into dry ice, as shown in Figure 5. The dry ice generation condition determination unit 73 determines that the dry ice generation conditions have been met when the change in pressure value shifts from decreasing (states A1 to A2 in Figure 5) to increasing (states A2 to A3 in Figure 5), and the amount of change in pressure value per unit time exceeds a predetermined reference value (states A2 to A3 in Figure 5). The reference value for the amount of change in pressure value used to determine that the dry ice generation conditions have been met is, for example, 3 kPa / second.

[0037] The pressurization control unit 74 pressurizes the system K using the pressurization unit 40A when the dry ice generation condition determination unit 73 determines that the dry ice generation conditions are met. Furthermore, as shown in Figure 5, the pressurization control unit 74 continues to pressurize the system K in the pressurization unit 40A if the pressure value is maintained within a range between a preset upper limit and lower limit with respect to the triple point pressure. This range can be set based on the triple point pressure, including an error range, etc.

[0038] Here, when the generated dry ice is reliquefied, the pressure and temperature of the liquefied carbon dioxide increase. Therefore, if the pressurization control unit 74 determines that the pressure has risen from the above range and the temperature detected by the temperature detection sensor 22 has risen above a preset temperature range according to the triple point pressure, it stops pressurizing the system K in the pressurization unit 40A.

[0039] The output unit 75 transmits command signals output from the pressurization control unit 74 via the communication module 65, namely command signals for controlling the on-off valves 13V, 13W, 14V, 18V, 41V, 42V and the lifting pump 15 to the on-off valves 13V, 13W, 14V, 18V, 41V, 42V and the lifting pump 15.

[0040] The information output unit 80 notifies the outside that the pressure value has fallen below the triple point pressure when the triple point pressure determination unit 72 determines that the pressure value has fallen below the triple point pressure. The information output unit 80 notifies the worker of the information that the pressure value has fallen below the triple point pressure in a manner that the worker can recognize. Such notification can be carried out, for example, by displaying it on a monitor, illuminating a warning lamp, outputting an alarm sound, or sending a message to a communication device such as a smartphone carried by the worker.

[0041] (Procedure for controlling liquefied carbon dioxide equipment) Figure 6 is a flowchart showing the procedure for a control method of a liquefied carbon dioxide facility according to an embodiment of this disclosure. As shown in Figure 6, the control method S10 for the liquefied carbon dioxide equipment according to this embodiment includes the steps of: acquiring a pressure value in S11; determining whether the pressure value is below the triple point pressure of carbon dioxide in S12; notifying the information in S13; determining whether the dry ice production conditions have been met in S14; determining whether the pressure value has recovered in S15; pressurizing the system in S16; determining whether the pressurization stop conditions have been met in S17; and stopping the pressurization in the system in S18.

[0042] The control method S10 for the liquefied carbon dioxide equipment is implemented when discharging liquefied carbon dioxide from tank 11 to the outside, or when loading liquefied carbon dioxide from the outside into tank 11, etc. The control method S10 for the liquefied carbon dioxide equipment may also be implemented when transferring liquid carbon dioxide between other tanks 11 located within the hull 2.

[0043] In step S11, which involves acquiring pressure values, the signal input unit 70 acquires the system pressure value K detected by the pressure detection sensor 21 and the system temperature value K detected by the temperature detection sensor 22.

[0044] In step S12, which determines whether the pressure value is less than or equal to the triple point pressure of carbon dioxide, the triple point pressure determination unit 72 determines whether the pressure value detected by the pressure detection sensor 21 is less than or equal to the triple point pressure of carbon dioxide. If it is determined that the pressure value is not below the triple point pressure of carbon dioxide (Step S12: No), return to step S11 and repeat the acquisition of pressure values ​​at predetermined time intervals. Furthermore, if it is determined in step S12 that the pressure value is below the triple point pressure of carbon dioxide (step S12: Yes), the on-off valve 18v is closed, and the discharge, loading, and transfer of liquefied carbon dioxide to and from the outside through the connection line 18 are interrupted, and the process proceeds to step S13.

[0045] In step S13, which involves broadcasting information, if it is determined in step S12 that the pressure value of K within the system is below the triple point pressure of carbon dioxide (states A1 to A2 in Figure 5), the information output unit 80 broadcasts information to the outside indicating that the pressure value within the system is below the triple point pressure. Upon receiving the information broadcast in step S13, the worker investigates the cause of the drop in the pressure value of K within the system below the triple point pressure of carbon dioxide, and takes countermeasures if the cause is manageable. Possible causes of the drop in the pressure value of K within the system below the triple point pressure of carbon dioxide include, for example, incorrect operation of various parts, poor connections at the piping connections of various parts, and leaks from valves of various parts.

[0046] In step S14, which determines whether the dry ice generation conditions have been met, the system determines whether the pressure value has met the predetermined dry ice generation conditions, given that step S12 determined the pressure value is below the triple point pressure of carbon dioxide. The dry ice generation condition determination unit 73 determines that the dry ice generation conditions have been met when the change in pressure value changes from decreasing (state A2 in Figure 5) to increasing, and the amount of change in pressure value per unit time becomes equal to or greater than a predetermined reference value (states A2 to A3 in Figure 5). If it is determined in step S14 that the conditions for dry ice generation are not met (step S14: No), proceed to step S15.

[0047] In step S15, which determines whether the pressure value has recovered, it is determined whether the pressure value of K in the system detected by the pressure detection sensor 21 after step S13 has recovered to or above the triple point pressure. For example, if a worker who has received information in step S13 indicating that the pressure value in the system is below the triple point pressure resolves the cause of the pressure value dropping below the triple point pressure of carbon dioxide, the pressure value will stop decreasing and recover to or above the triple point pressure. Therefore, if it is determined in step S15 that the pressure value has recovered to or above the triple point pressure (step S15; Yes), the process is terminated. If it is not determined in step S15 that the pressure value has recovered to or above the triple point pressure (step S15; No), the process returns to step S14.

[0048] Figure 7 shows the state in which pressurization is being performed by the pressurizing unit in the liquefied carbon dioxide facility shown in Figure 2. If it is determined in step S14 that the dry ice generation conditions have been met (step S14: Yes), the process proceeds to step S16, which involves pressurizing the system. In step S16, the system K is pressurized by the pressurizing unit 40A. At this time, as shown in Figure 7, the on-off valves 13v, 13w, 14v, and 18v are closed to shut off the system K. In this state, the on-off valves 41v and 42V are opened, and carbon dioxide gas is sent into the system K from an external pressure supply source through the pressurizing line 41, thereby pressurizing the system K. By pressurizing the system K, the pressure of the liquid carbon dioxide in the system K increases, and the dry ice that has begun to be generated is reliquefied. At this time, if it is determined that the dry ice generation conditions have been met and the liquefied carbon dioxide is in a mixed phase state of gas, liquid, and dry ice, the dry ice can be reliquefied in a short time by immediately pressurizing the system K.

[0049] In step S17, which determines whether the pressurization stop condition has been met, it is determined whether the dry ice that began to be generated after the start of step S16 has been reliquefied. In this embodiment, for example, it is determined whether the temperature of the system K detected by the temperature detection sensor 22 has risen by more than a preset temperature range after the pressurization of the system K has started. If the temperature of the system K has risen by more than a preset temperature range, the pressurization control unit 74 determines that the dry ice has been reliquefied and the pressurization stop condition has been met. If it is determined that the conditions for stopping the pressurization have not been met (Step S17: No), the pressurization of the system K by the pressurization unit 40A will continue. Furthermore, if it is determined that the conditions for stopping the pressurization have been met (Step S17: Yes), the process proceeds to Step S18, where the pressurization of K within the system is stopped by the pressurization unit 40A. After the pressurization is stopped, the discharge, loading, and transfer of liquefied carbon dioxide to and from the outside through the connection line 18 are resumed.

[0050] Figure 8 shows an example of the changes in pressure and temperature of liquefied carbon dioxide when pressurized by the pressurizing unit, and when not pressurized by the pressurizing unit. As shown in Figure 8, when it is determined in step S14 that the dry ice generation conditions are met, and the system K is immediately pressurized in step S16 by the pressurizing unit 40A (in Figure 8, "Pressurized"), the pressure value of the system K immediately rises and maintains a pressure value corresponding to the pressurization. Then, as the dry ice generated in the liquefied carbon dioxide is reliquefied by the pressurization of the system K, the temperature of the system K rises. In contrast, if pressurization is not performed by the pressurizing unit 40A at the time it is determined that the conditions for dry ice generation are met, the carbon dioxide, which was in a mixed phase state of gas, liquid, and dry ice (solid), will continue to dry out. When the internal K of the system is closed and the cause of the internal K pressure value dropping below the triple point pressure is eliminated (in Figure 8, "Unpressurized"), the internal K pressure will gradually rise naturally, and eventually the generated dry ice will reliquefy, causing the temperature to rise. Compared to the case where pressurization is not performed by the pressurizing unit 40A, pressurizing by the pressurizing unit 40A significantly shortens the time it takes for the dry ice to reliquefy.

[0051] (Effects and Benefits) In the liquefied carbon dioxide equipment 10A, ship 1, and control method S10 of the first embodiment described above, it is determined whether the pressure value of K in the system is below the triple point pressure of carbon dioxide, and further, when it is determined that the pressure value of K in the system is below the triple point pressure, it is determined whether the change in the pressure value of K in the system satisfies the dry ice generation conditions. After liquefied carbon dioxide's pressure falls below the triple point pressure, it remains in a liquid state and continues to decrease in pressure. Then, as the liquefied carbon dioxide begins to transform from a liquid into dry ice, its pressure rises sharply. The change in pressure due to this rapid increase satisfies the conditions for dry ice formation, allowing for a more direct understanding of dry ice formation. Furthermore, if the conditions for dry ice generation are determined to be met, the dry ice generated in the system can be rapidly reliquefied by pressurizing the system's K. As a result, the dry ice formation process can be monitored with high accuracy, and its formation can be suppressed more effectively.

[0052] Furthermore, in the first embodiment described above, when the change in pressure value shifts from decreasing to increasing, and the amount of change in pressure value per unit time exceeds a predetermined reference value, it is determined that the conditions for dry ice production have been met. This allows for highly accurate detection of the change in the state of liquefied carbon dioxide when it turns from a liquid state to dry ice after the pressure of liquefied carbon dioxide falls below the triple point pressure, based on the change in the pressure value K within the system.

[0053] Furthermore, in the first embodiment described above, if it is determined that the pressure value is below the triple point pressure, the information output unit 80 notifies the outside that the pressure value is below the triple point pressure, and based on this notification, measures can be taken to address the cause of the pressure value falling below the triple point pressure. Therefore, the process of the multiphase carbon dioxide in K within the system turning into dry ice can be suppressed.

[0054] Furthermore, in the first embodiment described above, the pressurizing section 40A can supply carbon dioxide gas at a higher pressure than that in the system K from an external pressure source to the system K, thereby pressurizing the system K and reliquefying the dry ice that has formed in the system K.

[0055] <Second Embodiment> Next, a second embodiment of the liquefied carbon dioxide equipment, vessel, and control method for the liquefied carbon dioxide equipment according to this disclosure will be described. In the second embodiment described below, only the configuration of the pressurization section of the liquefied carbon dioxide equipment differs from the first embodiment. Therefore, the flowchart in Figure 6 will be used as a reference, and the same parts as in the first embodiment will be denoted by the same reference numerals, and redundant explanations will be omitted. Figure 9 shows the configuration of a liquefied carbon dioxide facility according to the second embodiment of this disclosure. As shown in Figure 9, the liquefied carbon dioxide equipment 10B of the second embodiment includes a tank 11, a piping section 100, a pressure detection sensor 21, a temperature detection sensor 22, a pressurization section 40B, a control device 60, and an information output section 80.

[0056] In this second embodiment, the pressurizing unit 40B is configured to pressurize the system K. In this embodiment, the pressurizing unit 40B connects the gas phase in the tank 11 with the system K, thereby supplying carbon dioxide gas from the gas phase in the tank 11 to the system K and pressurizing the system K.

[0057] Figure 10 shows the state in which pressurization is being performed by the pressurizing unit in the liquefied carbon dioxide facility shown in Figure 9. As shown in Figure 10, in step S16 (see Figure 6) of pressurizing the system K, the pressurizing unit 40B closes valves 13w, 14v, and 18v, and then opens valve 13v, thereby supplying gaseous carbon dioxide gas from the tank 11 to the system K through the upper loading line 13A. The pressurizing unit 40B may also be equipped with a pump or compressor (not shown) to increase the pressure of the carbon dioxide gas supplied to the system K through the upper loading line 13A. The pressurizing unit 40B supplies carbon dioxide gas at a higher pressure to the system K, causing the pressure in the system K to rise and reliquefying the dry ice contained in the liquefied carbon dioxide.

[0058] As shown in Figure 9, the liquefied carbon dioxide equipment 10B in this second embodiment further includes a liquid supply unit 48 that supplies the liquid in the tank 11 to the system K which is pressurized by the pressurizing unit 40B. In this second embodiment, a discharge line 14 and a lifting pump 15 are used as the liquid supply unit 48.

[0059] Furthermore, the liquefied carbon dioxide equipment 10B in this second embodiment is equipped with a return line 49. One end of the return line 49 is connected to the piping section 100 in the system K, and the other end is located inside the tank 11 and is open. An on / off valve 49v is provided in the middle of the return line 49. A strainer 49s is provided in the return line 49. The strainer 49s recovers dry ice particles contained in the liquid. The specific configuration of the strainer 49s is not limited in any way.

[0060] Figure 11 shows the state in which liquid is being supplied by the liquid supply unit in the liquefied carbon dioxide facility shown in Figure 9. As shown in Figure 11, in the liquid supply unit 48, with the on-off valves 13v, 13w, and 18v closed, the on-off valves 14v and 49v are opened to operate the lifting pump 15. As a result, liquefied carbon dioxide (liquid) from the liquid phase in the tank 11 is sent to the system K through the discharge line 14, and the dry ice remaining in the system K, which is pressurized by the pressurization unit 40B, is pulverized. When the liquid supply unit 48 supplies liquefied carbon dioxide to the system K, the liquid pushed out from the system K is returned to the tank 11 through the return line 49. At this time, dry ice particles contained in the liquefied carbon dioxide flowing through the return line 49 are collected by the strainer 49s, and their inflow into the tank 11 is suppressed.

[0061] (Effects and Benefits) In the liquefied carbon dioxide equipment 10B of the second embodiment described above, similar to the first embodiment, the dry ice generation status can be grasped with high accuracy, and the generation of dry ice can be suppressed more effectively.

[0062] Furthermore, in the second embodiment described above, by connecting the gas phase in the tank 11 with the system K in the pressurizing section 40B, the carbon dioxide gas in the gas phase of the tank 11 pressurizes the system K, and the dry ice generated in the system K can be reliquefied.

[0063] Furthermore, in the second embodiment described above, the liquid supply unit 48 connects the liquid phase in the tank 11 to the system K pressurized by the pressurizing unit 40B, and supplies the liquid in the tank 11 to the system K, thereby pulverizing the dry ice remaining in the system K pressurized by the pressurizing unit 40B.

[0064] Furthermore, in the second embodiment described above, since a strainer 49s is provided in the return line 49, when the liquid supplied to the system K is returned to the tank 11, dry ice particles contained in the liquid can be recovered. This prevents dry ice contained in the liquid from flowing into the tank 11.

[0065] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure. In the embodiments and modifications described above, a portion of the piping section 100 is designated as the system area K. However, the area designated as the system area K may be an area other than those described above. For example, the system area K may be set in another part of the piping section 100, or it may be set inside the tank 11. Furthermore, the system area K may be set across the piping section 100 and the tank 11.

[0066] Furthermore, in the above embodiments and modifications, the liquefied carbon dioxide equipment 10A and 10B are provided on the ship 1, but this is not the only way to do so. The liquefied carbon dioxide equipment 10A and 10B can also be applied to floating structures, onshore storage facilities, and the like.

[0067] <Note> The control method S10 for the liquefied carbon dioxide equipment 10A, 10B, ship 1, and liquefied carbon dioxide equipment 10A, 10B described in each embodiment can be understood, for example, as follows.

[0068] (1) The liquefied carbon dioxide equipment 10A and 10B according to the first embodiment comprises a tank 11 capable of storing liquefied carbon dioxide, a piping section 100 connected to the tank 11 through which the liquefied carbon dioxide can flow, a pressure detection sensor 21 that detects the pressure value of the system K in which the liquefied carbon dioxide is present inside at least one of the tank 11 and the piping section 100, pressurizing sections 40A and 40B capable of pressurizing the system K, and a control device 60 that controls the pressurizing sections 40A and 40B, wherein the control device 60 determines that the pressure value detected by the pressure detection sensor 21 is carbon dioxide The system includes: a triple point pressure determination unit 72 that determines whether the pressure is below the triple point pressure of carbon dioxide; a dry ice generation condition determination unit 73 that, when the triple point pressure determination unit 72 determines that the pressure is below the triple point pressure of carbon dioxide, determines whether the change in the pressure detected by the pressure detection sensor 21 satisfies predetermined dry ice generation conditions; and a pressurization control unit 74 that, when the dry ice generation condition determination unit 73 determines that the dry ice generation conditions are met, pressurizes the system K using the pressurization units 40A and 40B.

[0069] After liquefied carbon dioxide's pressure falls below the triple point pressure, it remains in a liquid state, and its pressure continues to decrease. Subsequently, when liquefied carbon dioxide begins to transform from a liquid into dry ice, its pressure rises sharply. The change in pressure due to this rapid increase satisfies the conditions for dry ice formation, allowing for a more direct understanding of dry ice formation. Furthermore, if the conditions for dry ice generation are determined to be met, the dry ice generated in the system can be rapidly reliquefied by pressurizing the system's K. As a result, the dry ice formation process can be monitored with high accuracy, and its formation can be suppressed more effectively.

[0070] (2) The liquefied carbon dioxide equipment 10A and 10B according to the second embodiment are the liquefied carbon dioxide equipment 10A and 10B of (1), wherein the dry ice generation condition determination unit 73 determines that the dry ice generation conditions have been met when the change in the pressure value changes from a decrease to an increase, and the amount of change in the pressure value per unit time becomes equal to or greater than a predetermined standard value.

[0071] This allows for highly accurate detection of the state change of liquefied carbon dioxide when it transforms from a liquid to dry ice after its pressure falls below the triple point pressure, based on the change in the pressure value K within the system.

[0072] (3) The liquefied carbon dioxide equipment 10A, 10B according to the third embodiment is the liquefied carbon dioxide equipment 10A, 10B according to (1) or (2), further comprising an information output unit 80 that notifies the outside of information indicating that the pressure value is less than or equal to the triple point pressure when the triple point pressure determination unit 72 determines that the pressure value is less than or equal to the triple point pressure.

[0073] This allows for measures to be taken to address the cause of the pressure value falling below the triple point pressure. Consequently, the process of the multiphase carbon dioxide in the K phase of the system turning into dry ice can be suppressed.

[0074] (4) The liquefied carbon dioxide equipment 10A according to the fourth embodiment is any one of the liquefied carbon dioxide equipment 10A described in (1) to (3), wherein the pressurizing unit 40A pressurizes the system K by supplying carbon dioxide gas at a higher pressure than the system K from an external pressure source to the system K. An example of an external pressure source is another tank 11 connected to the tank 11 storing liquefied carbon dioxide.

[0075] This allows for the re-liquefaction of dry ice generated in system K by supplying carbon dioxide gas at a higher pressure than system K from an external pressure source to system K.

[0076] (5) The liquefied carbon dioxide equipment 10B according to the fifth embodiment is any one of the liquefied carbon dioxide equipment 10B described in (1) to (3), wherein the pressurizing unit 40B pressurizes the system K by connecting the gas phase in the tank 11 with the system K.

[0077] This allows the gas phase in tank 11 to communicate with system K, and the carbon dioxide gas in the gas phase of tank 11 to pressurize system K, thereby reliquefying the dry ice that has formed in system K.

[0078] (6) The liquefied carbon dioxide equipment 10B according to the sixth embodiment is the liquefied carbon dioxide equipment 10B according to (4) or (5), further comprising a liquid supply unit 48 that connects the liquid phase in the tank 11 to the system K which is pressurized by the pressurizing unit 40B, and supplies the liquid in the tank 11 to the system K.

[0079] As a result, the liquid supply unit 48 connects the liquid phase in the tank 11 to the pressurized system K in the pressurized unit 40B, and supplies the liquid in the tank 11 to the system K, thereby pulverizing the dry ice remaining in the pressurized system K in the pressurized unit 40B.

[0080] (7) The liquefied carbon dioxide equipment 10B according to the seventh embodiment is the liquefied carbon dioxide equipment 10B of (6), further comprising a return line 49 that returns the liquid supplied from the liquid supply unit 48 to the system K back into the tank 11, and the return line 49 is provided with a strainer 49s for recovering dry ice particles contained in the liquid.

[0081] As a result, since a strainer 49s is provided in the return line 49, when the liquid supplied to the system K is returned to the tank 11, dry ice particles contained in the liquid can be recovered. This prevents dry ice contained in the liquid from flowing into the tank 11.

[0082] (8) The vessel 1 according to the eighth aspect comprises a hull 2 ​​and one of the liquefied carbon dioxide equipment 10A or 10B from (1) to (7).

[0083] This makes it possible to provide a vessel 1 equipped with liquefied carbon dioxide equipment 10A and 10B that can accurately grasp the dry ice generation status and more effectively suppress dry ice generation.

[0084] (9) A control method S10 for liquefied carbon dioxide equipment 10A, 10B according to the ninth embodiment includes a tank 11 capable of storing liquefied carbon dioxide, a piping section 100 connected to the tank 11 and through which the liquefied carbon dioxide can flow, a pressure detection sensor 21 for detecting the pressure value of a system K containing the liquefied carbon dioxide inside at least one of the tank 11 and the piping section 100, and pressurizing sections 40A, 40B capable of pressurizing the system K, the control method S10 for liquefied carbon dioxide equipment 10A, 10B, and includes a step S12 for determining whether the pressure value detected by the pressure detection sensor 21 is less than or equal to the triple point pressure of carbon dioxide, a step S14 for determining whether the pressure value satisfies predetermined dry ice generation conditions when it has been determined that the pressure value is less than or equal to the triple point pressure of carbon dioxide, and a step S16 for pressurizing the system K with the pressurizing sections 40A, 40B when it has been determined that the dry ice generation conditions are met.

[0085] According to the control method S10 for these liquefied carbon dioxide equipment 10A and 10B, the dry ice generation status can be grasped with high accuracy, and the generation of dry ice can be suppressed more effectively. [Explanation of Symbols]

[0086] 1 ship 2 hull 2a bow 2b stern 3A, 3B side 5 Upper Deck 7 Superstructure 8. Carbon dioxide storage compartment 10A, 10B Liquefied Carbon Dioxide Equipment 11 tanks 13 Loading Line 13A Upper loading line 13B Lower loading line 13V, 13W, 14V, 18V, 41V, 42V, 49V on / off valve 13s tip 14 Payout Line 15. Lifting pump 18 connection lines 21 Pressure detection sensor 22 Temperature detection sensors 40A, 40B pressurized section 41 Pressure line 42 ventilation lines 48 Liquid supply section 49 Return Line 49s Strainer 60 Control device 61 CPU 62 ROM 63 RAM Wireless 4 Storage 65 Communication Module 70 Signal Input Section 72 Triple Point Pressure Determination Unit 73 Dry ice generation condition determination unit 74 Pressurization Control Unit 75 Output section 80 Information Output Unit 100 Piping section Within the K system

Claims

1. A tank capable of storing liquefied carbon dioxide, A piping section connected to the aforementioned tank, through which the liquefied carbon dioxide can flow, A pressure detection sensor for detecting the pressure value in the system where the liquefied carbon dioxide is present, inside at least one of the tank and the piping section, A pressurizing section capable of pressurizing the inside of the system, The system comprises a control device for controlling the pressurizing section, The control device is A triple point pressure determination unit that determines whether the pressure value detected by the pressure detection sensor is less than or equal to the triple point pressure of carbon dioxide, The Triple Point Pressure Determination Unit determines that the pressure value is less than or equal to the triple point pressure of carbon dioxide, and the Dry Ice Production Condition Determination Unit determines whether the change in the pressure value detected by the pressure detection sensor satisfies predetermined dry ice production conditions. When the dry ice generation condition determination unit determines that the dry ice generation conditions are met, the pressurization control unit pressurizes the system using the pressurization unit, A liquefied carbon dioxide facility.

2. The dry ice generation condition determination unit determines that the dry ice generation conditions have been met when the change in the pressure value shifts from decreasing to increasing, and the amount of change in the pressure value per unit time becomes equal to or greater than a predetermined standard value. The liquefied carbon dioxide apparatus according to claim 1.

3. The triple-point pressure determination unit further comprises an information output unit that, when it determines that the pressure value is less than or equal to the triple-point pressure, notifies the outside of information indicating that the pressure value is less than or equal to the triple-point pressure. A liquefied carbon dioxide apparatus according to claim 1 or 2.

4. The pressurizing unit pressurizes the system by supplying carbon dioxide gas at a higher pressure than that inside the system from an external pressure source into the system. The liquefied carbon dioxide apparatus according to claim 1.

5. The pressurizing unit pressurizes the system by connecting the gas phase in the tank with the system. The liquefied carbon dioxide apparatus according to claim 1.

6. The system further comprises a liquid supply unit that connects the liquid phase in the tank to the pressurized system and supplies the liquid from the tank into the system. The liquefied carbon dioxide apparatus according to claim 4 or 5.

7. The system further includes a return line that returns the liquid supplied from the liquid supply unit to the tank. The return line is provided with a strainer for collecting dry ice particles contained in the liquid. The liquefied carbon dioxide apparatus according to claim 6.

8. The hull and, A liquefied carbon dioxide apparatus according to claim 1 or 2, A ship equipped with the following features.

9. A tank capable of storing liquefied carbon dioxide, A piping section connected to the aforementioned tank, through which the liquefied carbon dioxide can flow, A pressure detection sensor for detecting the pressure value in the system where the liquefied carbon dioxide is present, inside at least one of the tank and the piping section, A control method for a liquefied carbon dioxide facility comprising a pressurizing unit capable of pressurizing the system, The steps include determining whether the pressure value detected by the pressure detection sensor is less than or equal to the triple point pressure of carbon dioxide, The step of determining whether the pressure value satisfies predetermined dry ice production conditions, given that the pressure value is determined to be less than or equal to the triple point pressure of carbon dioxide, If it is determined that the dry ice generation conditions are met, the system is pressurized by the pressurizing unit, A control method for a liquefied carbon dioxide facility, including the equipment mentioned above.

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