Liquefied carbon dioxide facility and method for

Abstract

This liquefied carbon dioxide plant is provided with: a tank capable of storing liquefied carbon dioxide; a pipe connected to the tank and through which the liquefied carbon dioxide can flow; a pressure sensor that detects the pressure of a region in which liquefied carbon dioxide is present inside at least one of the tank and the pipe; a temperature sensor that detects the temperature of a region where liquefied carbon dioxide is present; and an estimation unit that estimates the generation status of dry ice in the region where liquefied carbon dioxide is present on the basis of the detection results of the pressure sensor and the temperature sensor.

Description

Technical Field

[0001] The present invention relates to liquefied carbon dioxide equipment and a method for estimating the generation status of dry ice.

[0002] This application claims priority from Japanese Patent Application No. 2022-133147 filed in Japan on August 24, 2022, and the contents are incorporated herein by reference. Background Art

[0003] For example, the tank (fuel tank) disclosed in Patent Document 1 includes a pipe (pipeline) for charging liquefied gas (LNG: Liquefied Natural Gas) into the tank and a pipe (pipeline) for discharging the liquefied gas from the tank.

[0004] When the pressure of liquefied carbon dioxide decreases in a tank storing liquefied carbon dioxide or in a pipe through which liquefied carbon dioxide flows, the liquefied carbon dioxide may solidify and generate dry ice for the following reasons.

[0005] The pressure of the triple point where the gas phase, liquid phase, and solid phase of liquefied carbon dioxide coexist (triple point pressure) is higher than the triple point pressure of LNG and LPG (liquefied petroleum gas), and sometimes the difference with the tank operating pressure during operation is small. In this case, depending on the tank operating pressure (tank design pressure), the pressure of liquefied carbon dioxide may become locally low, and the pressure of liquefied carbon dioxide may become lower than the triple point pressure, causing flash evaporation of liquefied carbon dioxide, and due to its latent heat of evaporation, the temperature of liquefied carbon dioxide drops and dry ice is generated.

[0006] When dry ice is generated in this way, the flow of liquefied carbon dioxide in the pipe may be blocked.

[0007] Therefore, in liquefied carbon dioxide equipment including a tank and piping for storing liquefied carbon dioxide, it is necessary to monitor the pressure of the area where liquefied carbon dioxide exists, such as inside the tank or piping, using a pressure sensor, and operate the equipment while managing the pressure to suppress the generation of dry ice.

[0008] Prior art literature

[0009] Patent Document 1: Japanese Patent Application No. 2018-528119 Summary of the invention

[0010] Problems to be solved by the invention

[0011] However, liquefied carbon dioxide obtained by recovering carbon dioxide from exhaust gas generated in various factories and the like and liquefying it often contains various impurities. The temperature and pressure of the triple point of such liquefied carbon dioxide containing impurities are sometimes different from the temperature and pressure of the triple point of liquefied carbon dioxide not containing impurities. Therefore, even in a pressure environment higher than the triple point of liquefied carbon dioxide not containing impurities, flash evaporation may occur in liquefied carbon dioxide containing impurities, and for example, even if the pressure in a region where liquefied carbon dioxide exists, such as in a tank or in a pipe, is monitored by a pressure sensor, dry ice may be generated.

[0012] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a liquefied carbon dioxide facility and a method for estimating a dry ice generation state, which can effectively suppress the generation of dry ice even when the liquefied carbon dioxide contains impurities.

[0013] Means for solving problems

[0014] In order to solve the above-mentioned problems, the liquefied carbon dioxide equipment of the present invention comprises: a tank, a pipe, a pressure sensor, a temperature sensor and an estimation unit. The tank can store liquefied carbon dioxide. The pipe is connected to the tank and can allow the liquefied carbon dioxide to flow. The pressure sensor detects the pressure of the area where the liquefied carbon dioxide exists inside at least one of the tank and the pipe. The temperature sensor detects the temperature of the area where the liquefied carbon dioxide exists. The estimation unit estimates the generation status of dry ice in the area where the liquefied carbon dioxide exists based on the detection results of the pressure sensor and the temperature sensor.

[0015] The liquefied carbon dioxide equipment of the present invention comprises: a tank, a pipe, a solid detection unit, and an estimation unit. The tank can store liquefied carbon dioxide. The pipe is connected to the tank and can allow the liquefied carbon dioxide to flow. The solid detection unit detects solids mixed in the liquefied carbon dioxide in the area where the liquefied carbon dioxide exists inside at least one of the tank and the pipe. The estimation unit estimates the generation status of dry ice in the area where the liquefied carbon dioxide exists based on the detection status of the solid by the solid detection unit.

[0016] The dry ice generation status estimation method of the present invention is a dry ice generation status estimation method in the liquefied carbon dioxide equipment as described above. The dry ice generation status estimation method includes a step of detecting pressure and temperature and a step of estimating dry ice generation status. In the step of detecting the pressure and temperature, the pressure and temperature of the area where the liquefied carbon dioxide exists are detected. In the step of estimating the dry ice generation status, the dry ice generation status in the area where the liquefied carbon dioxide exists is estimated based on the detection results of the pressure and the temperature.

[0017] The method for estimating the dry ice generation status of the present invention is a method for estimating the dry ice generation status in the liquefied carbon dioxide equipment as described above. The method for estimating the dry ice generation status includes a step of detecting the presence of a solid and a step of estimating the dry ice generation status. In the step of detecting the presence of the solid, it is detected whether there is a solid mixed in the liquefied carbon dioxide in the area where the liquefied carbon dioxide exists. In the step of estimating the dry ice generation status, the dry ice generation status in the area where the liquefied carbon dioxide exists is estimated based on the detection result of the solid.

[0018] Effects of the Invention

[0019] According to the liquefied carbon dioxide equipment and the dry ice generation state estimation method of the present invention, even when impurities are contained in the liquefied carbon dioxide, the generation of dry ice can be effectively suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing a schematic configuration of a liquefied carbon dioxide facility according to a first embodiment of the present invention.

[0021] Figure 2 It is a cross-sectional view showing a pressure sensor and a temperature sensor provided in the pipe according to the first and second embodiments of the present invention.

[0022] Figure 3 It is a diagram showing the hardware configuration of the control device according to the first to third embodiments of the present invention.

[0023] Figure 4 This is a functional block diagram of the control device according to the first and second embodiments of the present invention.

[0024] Figure 5 This is a flowchart showing the steps of the dry ice generation status estimation method according to the first embodiment of the present invention.

[0025] Figure 6 This is a diagram showing a schematic configuration of a liquefied carbon dioxide plant according to a second embodiment of the present invention.

[0026] Figure 7 It is a diagram showing a solid detection unit according to the second and third embodiments of the present invention.

[0027] Figure 8 This is a flowchart showing the steps of a method for estimating a dry ice generation state according to a second embodiment of the present invention.

[0028] Fig. 9 This is a diagram showing a schematic configuration of a liquefied carbon dioxide plant according to a third embodiment of the present invention.

[0029] Fig.10This is a functional block diagram of a control device according to a third embodiment of the present invention.

[0030] Fig.11 This is a flowchart showing the steps of a method for estimating a dry ice generation state according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0031] <First embodiment>

[0032] Below, refer to Figure 1 to Figure 11 Next, a liquefied carbon dioxide facility and a method for estimating a dry ice generation state according to an embodiment of the present invention will be described.

[0033] (Overall structure of liquefied carbon dioxide equipment)

[0034] like Figure 1 As shown, the liquefied carbon dioxide plant 1A of this embodiment includes at least a tank 2, a pipe 10, a pressure sensor 20, a temperature sensor 30, and a control device 60A.

[0035] The tank 2 can store liquefied carbon dioxide. The liquefied carbon dioxide stored in the tank 2 may also be mixed with impurities. In the following description, the liquid containing the liquefied carbon dioxide and the impurities mixed in the liquefied carbon dioxide is referred to as the storage liquid L. The tank 2 is installed in the hull of a ship, the floating body of an offshore floating device, a liquefied gas storage facility on land, etc.

[0036] The tank 2 is, for example, cylindrical. The tank 2 includes a cylindrical portion 3 and an end plate portion 4. The cylindrical portion 3 extends in a central axis direction Dc in which the central axis thereof extends. In this embodiment, the central axis direction Dc is a direction perpendicular to the up-down direction Dv. The central axis direction Dc may be consistent with the horizontal direction, or may be slightly inclined relative to the horizontal direction. In this embodiment, the cylindrical portion 3 is formed in a cylindrical shape, and a cross-sectional shape perpendicular to the central axis direction Dc thereof is circular. The end plate portions 4 are respectively arranged at both ends of the cylindrical portion 3 in the central axis direction Dc. Each end plate portion 4 is hemispherical, and respectively closes the openings on both sides of the central axis direction Dc of the cylindrical portion 3.

[0037] The tank 2 may be arranged so that its central axis direction Dc coincides with the vertical direction Dv. The tank 2 is not limited to a cylindrical shape, but may be in other shapes such as a spherical shape or a square shape.

[0038] The liquefied carbon dioxide equipment 1A of this embodiment includes, for example, a loading pipe 11 and a discharge pipe 12 as pipes 10. The loading pipe 11 and the discharge pipe 12 are connected to the tank 2, respectively. The loading pipe 11 and the discharge pipe 12 as pipes 10 can each allow the storage liquid L of liquefied carbon dioxide to flow. The pipe 10 can be any pipe connected to the tank 2, and is not limited to the loading pipe 11 and the discharge pipe 12, and may be a pipe for other purposes.

[0039] The loading pipe 11 is a pipe for loading the storage liquid L of liquefied carbon dioxide supplied from the outside into the tank 2. The loading pipe 11 passes through the top of the tank 2, for example, and extends from the upper side to the lower side in the vertical direction Dv inside and outside the tank 2. The front end of the loading pipe 11 (in other words, the lower end in the vertical direction Dv) opens downward at the lower part inside the tank 2.

[0040] The loading pipe 11 is provided with an on-off valve 15. The on-off valve 15 is disposed, for example, outside the tank 2. The on-off valve 15 opens and closes the loading pipe 11.

[0041] The discharge pipe 12 is a pipe for discharging the storage liquid L in the tank 2 to the outside of the tank 2. The discharge pipe 12 extends from the outside of the tank 2 through the top of the tank 2, for example, to the inside of the tank 2. The front end of the discharge pipe 12 is arranged at the lower part of the tank 2. A pump 13 is provided at the front end of the discharge pipe 12. The pump 13 is arranged in the tank 2. The pump 13 sucks the storage liquid L of liquefied carbon dioxide in the tank 2 and sends it to the outside of the tank 2 through the discharge pipe 12.

[0042] The discharge pipe 12 is provided with an on-off valve 16. The on-off valve 16 is disposed, for example, outside the tank 2. The on-off valve 16 opens and closes the discharge pipe 12.

[0043] The interior of the tank 2, the interior of the loading pipe 11, and the interior of the discharge pipe 12 are regions where liquefied carbon dioxide exists.

[0044] (Structure of pressure sensor and temperature sensor)

[0045] The pressure sensor 20 detects the pressure of the region where the liquefied carbon dioxide exists inside the tank 2 and inside the pipe 10. In the present embodiment, the pressure sensor 20 includes, for example, first to fifth pressure sensors 20A to 20E.

[0046] Among them, the first pressure sensor 20A, the second pressure sensor 20B and the third pressure sensor 20C detect the pressure of each part in the tank 2. The first pressure sensor 20A detects the pressure of the upper part in the tank 2. The second pressure sensor 20B detects the pressure of the bottom part in the tank 2. The third pressure sensor 20C detects the pressure of the middle part above the bottom part in the tank 2. The number and configuration of the pressure sensors 20 provided in the tank 2 are not limited in any way. In addition to the first pressure sensor 20A, the second pressure sensor 20B and the third pressure sensor 20C, other pressure sensors 20 may be provided. In addition, part of the first pressure sensor 20A, the second pressure sensor 20B and the third pressure sensor 20C may be omitted.

[0047] Figure 2It is a cross-sectional view showing a pressure sensor and a temperature sensor provided in the pipe according to the embodiment of the present invention.

[0048] like Figure 2 As shown, the fourth pressure sensor 20D and the fifth pressure sensor 20E detect the pressure of each part in the pipe 10. The fourth pressure sensor 20D and the fifth pressure sensor 20E are provided in each pipe of the loading pipe 11 and the discharge pipe 12. The fourth pressure sensor 20D detects the pressure near the pipe wall in the pipe 10. The fifth pressure sensor 20E detects the pressure of the middle part of the pipe 10 away from the pipe wall.

[0049] The number and arrangement of the pressure sensors provided in the pipe 10 are not limited in any way, and other pressure sensors 20 may be provided in addition to the fourth pressure sensor 20D and the fifth pressure sensor 20E. In addition, a plurality of sets of the fourth pressure sensor 20D and the fifth pressure sensor 20E may be provided at intervals in the extending direction of the pipe 10.

[0050] The temperature sensor 30 detects the temperature of the region where the liquefied carbon dioxide exists inside the tank 2 and the pipe 10. In the present embodiment, the temperature sensor 30 includes, for example, first to fifth temperature sensors 30A to 30E.

[0051] like Figure 1 As shown, the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C detect the temperature of the storage liquid L of the liquefied carbon dioxide at each part of the tank 2. The first temperature sensor 30A detects the temperature of the upper part of the tank 2. The second temperature sensor 30B detects the temperature of the bottom of the tank 2. The third temperature sensor 30C detects the temperature of the middle part above the bottom of the tank 2. As the first temperature sensor 30A and the second temperature sensor 30B, for example, a thermal camera or the like can be used. As the third temperature sensor 30C, for example, a thermocouple or the like can be used.

[0052] The number and arrangement of the temperature sensors 30 provided in the tank 2 are not limited in any way, and in addition to the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C, other temperature sensors 30 may be provided. In addition, a part of the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C may be omitted.

[0053] like Figure 2As shown, the fourth temperature sensor 30D and the fifth temperature sensor 30E detect the temperature of each part in the pipe 10. The fourth temperature sensor 30D and the fifth temperature sensor 30E are provided in each pipe of the loading pipe 11 and the discharge pipe 12. The fourth temperature sensor 30D detects the pressure near the pipe wall of the pipe 10. The fifth temperature sensor 30E detects the temperature of the middle part of the pipe 10 away from the pipe wall. As the fourth temperature sensor 30D, for example, a thermal camera or the like can be used. As the fifth temperature sensor 30E, for example, a thermocouple or the like can be used.

[0054] The number and arrangement of the temperature sensors provided in the pipe 10 are not limited, and other temperature sensors 30 may be provided in addition to the fourth temperature sensor 30D and the fifth temperature sensor 30E. In addition, a plurality of sets of the fourth temperature sensor 30D and the fifth temperature sensor 30E may be provided at intervals in the extending direction of the pipe 10.

[0055] (Hardware structure diagram)

[0056] Figure 3 It is a diagram showing the hardware configuration of the control device according to the embodiment of the present invention.

[0057] like Figure 3 As shown, the control device 60A is a computer including a CPU 61 (Central Processing Unit), a ROM 62 (Read Only Memory), a RAM 63 (Random Access Memory), a memory 64 such as a HDD (Hard Disk Drive), and a signal transceiver module 65 .

[0058] (Functional Block Diagram)

[0059] Figure 4 This is a functional block diagram of a control device according to an embodiment of the present invention.

[0060] like Figure 4 As shown, the CPU 61 of the control device 60A implements the functional configurations of the signal input unit 70, the storage unit 71, the estimation unit 72A, the control unit 73A, and the output unit 75 by executing a program pre-stored in the memory 64 or the like. The control device 60A estimates the generation status of dry ice in the area where liquefied carbon dioxide exists based on the detection results of the pressure sensor 20 and the temperature sensor 30.

[0061] The signal input unit 70 receives detection signals from the pressure sensor 20 and the temperature sensor 30 via the signal transceiver module 65 .

[0062] The storage unit 71 stores information on the triple point based on the composition of the storage liquid L of liquefied carbon dioxide stored in the tank 2. The storage liquid L of liquefied carbon dioxide contains liquefied carbon dioxide and impurities mixed in the liquefied carbon dioxide. The pressure and temperature of the triple point of such storage liquid L are different from those of liquefied carbon dioxide that does not contain impurities. In addition, the pressure and temperature of the triple point are different depending on the amount of impurities in the storage liquid L relative to the liquefied carbon dioxide. Therefore, before the storage liquid L of liquefied carbon dioxide is stored in the tank 2, the composition of the storage liquid L is analyzed, and the information on the triple point including the pressure and temperature of the triple point of the storage liquid L is obtained in advance. The obtained triple point information is stored in the storage unit 71.

[0063] The estimation unit 72A estimates the generation status of dry ice in the region where liquefied carbon dioxide exists based on the detection results of the pressure sensor 20 and the temperature sensor 30. The estimation unit 72A obtains the detection results of the pressure of the storage liquid L in the region where liquefied carbon dioxide exists in the tank 2 and the pipe 10 obtained by the pressure sensor 20 (the first pressure sensor 20A to the fifth pressure sensor 20E) based on the detection signal from the pressure sensor 20 received by the signal input unit 70. The estimation unit 72A obtains the detection results of the temperature of the storage liquid L in the region where liquefied carbon dioxide exists in each part of the tank 2 and the pipe 10 obtained by the temperature sensor 30 (the first temperature sensor 30A to the fifth temperature sensor 30E) based on the detection signal from the temperature sensor 30 received by the signal input unit 70.

[0064] The estimation unit 72A estimates the generation status of dry ice based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the triple point information stored in the storage unit 71. The estimation unit 72A compares the acquired pressure and temperature of the storage liquid L in the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the storage liquid L based on the information of the triple point of the storage liquid L stored in the storage unit 71. When the pressure of the storage liquid L in the region where the liquefied carbon dioxide exists is lower than the pressure of the triple point of the storage liquid L and the temperature of the storage liquid L in the region where the liquefied carbon dioxide exists is higher than the temperature of the triple point of the storage liquid L, the estimation unit 72A estimates that dry ice is generated in the storage liquid L in the region where the liquefied carbon dioxide exists.

[0065] The control unit 73A controls the operations of the pump 13 and the on-off valves 15 and 16 to suppress the generation of dry ice based on the generation status of dry ice estimated by the estimation unit 72A.

[0066] When the estimating unit 72A estimates that dry ice is being generated, the control unit 73A, for example, stops the operation of the pump 13 to suppress the pressure drop in the tank 2. In addition, when the estimating unit 72A estimates that dry ice is being generated, the control unit 73A may, for example, increase the rotation speed of the pump 13 to pressurize the storage liquid L of the liquefied carbon dioxide in the pipe 10.

[0067] Furthermore, when the estimating unit 72A estimates that dry ice is being generated, the control unit 73A may close the on-off valves 15 and 16 to restore the static pressure in the pipe 10 .

[0068] The control unit 73A may control the operation of the pump 13 and the on-off valves 15 and 16 in whole or in part. In addition, the control unit 73A may control the operation of the pump 13 and the on-off valves 15 and 16 at the same time or at different times. In addition to the above, the control unit 73A may supply pressurized fluid to the area where liquefied carbon dioxide exists.

[0069] (Steps of a method for estimating dry ice generation conditions)

[0070] Figure 5 This is a flowchart showing the steps of a method for estimating a dry ice generation state according to an embodiment of the present invention.

[0071] like Figure 5 As shown, the dry ice generation condition estimation method S10 of the present embodiment includes the following steps: a step S11 of detecting pressure and temperature; a step S12 of estimating the dry ice generation condition; a step S13 of determining whether the dry ice generation condition exists; and a step S14 of controlling the operation of a pump and an opening and closing valve.

[0072] In the step S11 of detecting pressure and temperature, the pressure and temperature of the area in which the liquefied carbon dioxide exists in the tank 2 and the pipe 10 are detected by the pressure sensor 20 and the temperature sensor 30. For this purpose, the first pressure sensor 20A, the second pressure sensor 20B, and the third pressure sensor 20C detect the pressure of each part in the tank 2. In addition, the fourth pressure sensor 20D and the fifth pressure sensor 20E detect the pressure of each part in the pipe 10. In addition, the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C detect the temperature of each part in the tank 2. In addition, the fourth temperature sensor 30D and the fifth temperature sensor 30E detect the temperature of each part in the pipe 10.

[0073] Detection signals indicating detection results of the pressure sensor 20 and the temperature sensor 30 are transmitted to the control device 60A.

[0074] In step S12 of estimating the dry ice generation status, the dry ice generation status in the area where the liquefied carbon dioxide exists is estimated based on the detection results of the pressure and temperature. For this purpose, the signal input unit 70 of the control device 60A receives the detection signals of the pressure sensor 20 and the temperature sensor 30. And the estimation unit 72A obtains the detection results of the pressure of the storage liquid L in each part of the tank 2 and the pipe 10 by the pressure sensor 20 (the first pressure sensor 20A to the fifth pressure sensor 20E) based on the detection signal from the pressure sensor 20 received by the signal input unit 70. In addition, the estimation unit 72A obtains the detection results of the temperature of the storage liquid L in each part of the tank 2 and the pipe 10 by the temperature sensor 30 (the first temperature sensor 30A to the fifth temperature sensor 30E) based on the detection signal from the temperature sensor 30 received by the signal input unit 70. And the estimation unit 72A obtains the information of the triple point of the storage liquid L stored in the storage unit 71.

[0075] In the step S12 of estimating the generation status of dry ice, the generation status of dry ice is further estimated by the estimating unit 72A based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the triple point information stored in the storage unit 71. For this purpose, the pressure and temperature of the storage liquid L in the region where the liquefied carbon dioxide exists obtained by the estimating unit 72A are compared with the pressure and temperature of the triple point of the storage liquid L based on the information of the triple point of the storage liquid L stored in the storage unit 71. Here, when the pressure of the storage liquid L in the region where the liquefied carbon dioxide exists is lower than the pressure of the triple point of the storage liquid L and the temperature of the storage liquid L in the region where the liquefied carbon dioxide exists is higher than the temperature of the triple point of the storage liquid L, the estimating unit 72A estimates that dry ice is generated in the storage liquid L in the region where the liquefied carbon dioxide exists.

[0076] In step S13 of determining whether dry ice is being generated, it is determined whether dry ice is being generated in the storage liquid L in the region where liquefied carbon dioxide is present in step S12. If the result of this determination is that dry ice is not being generated in the storage liquid L in the region where liquefied carbon dioxide is present (No in step S13), the process returns to step S11.

[0077] On the other hand, when it is determined that dry ice is generated in the storage liquid L in the region where liquefied carbon dioxide exists (YES in step S13 ), the process proceeds to step S14 .

[0078] In step S14 of controlling the operation of the pump and the on-off valve, when it is determined in step S13 that dry ice is generated in the storage liquid L, the operation of the pump 13 and the on-off valves 15 and 16 is controlled by the control unit 73A. For example, the control unit 73A stops the operation of the pump 13 to suppress the pressure drop in the tank 2. In addition, the control unit 73A may increase the rotation speed of the pump 13 to pressurize the storage liquid L (liquefied carbon dioxide) in the pipe 10. In addition, the control unit 73A closes the on-off valves 15 and 16 to restore the static pressure in the pipe 10. In this way, the growth of dry ice is suppressed and the generated dry ice is eliminated.

[0079] (Effect)

[0080] In the liquefied carbon dioxide equipment 1A of the above-mentioned embodiment, the pressure and temperature of the region where the liquefied carbon dioxide exists inside at least one of the tank 2 and the pipe 10 are detected by the pressure sensor 20 and the temperature sensor 30. Thus, even when the liquefied carbon dioxide contains impurities, the estimation unit 72A can compare the pressure and temperature of the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the liquefied carbon dioxide containing impurities based on the detection results of the pressure sensor 20 and the temperature sensor 30. Thus, the generation status of dry ice in the region where the liquefied carbon dioxide exists can be estimated with high accuracy. Therefore, even when the liquefied carbon dioxide contains impurities, the generation of dry ice can be effectively suppressed.

[0081] In addition, in the above-described embodiment, the storage unit 71 stores information on the triple point based on the composition of the storage liquid L of liquefied carbon dioxide stored in the tank 2. The estimating unit 72A estimates the generation status of dry ice based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the information on the triple point stored in the storage unit 71. Thus, the generation status of dry ice in the storage liquid L of liquefied carbon dioxide containing impurities can be estimated with higher accuracy.

[0082] In addition, in the above-mentioned embodiment, the control unit 73A controls the operation of the pump 13 based on the dry ice generation condition estimated by the estimation unit 72A. Therefore, when the estimation unit 72A estimates that dry ice is generated, it is possible to suppress the generation of dry ice and eliminate the generated dry ice by controlling the operation of the pump 13. As control of the operation of the pump 13, for example, there are stopping the operation of the pump 13 and pressurizing the liquid carbon dioxide by the pump 13.

[0083] Furthermore, in the above-described embodiment, when the estimating unit 72A estimates that the situation is one in which dry ice is generated, the generation of dry ice can be suppressed by closing the on-off valves 15 and 16 .

[0084] In the dry ice generation state estimation method S10 of the above-mentioned embodiment, the dry ice generation state in the region where the liquefied carbon dioxide exists is estimated based on the detection results of the pressure and temperature of the region where the liquefied carbon dioxide exists. By comparing the detection results of the pressure and temperature of the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the liquefied carbon dioxide containing impurities, the generation of dry ice can be effectively suppressed even when the liquefied carbon dioxide contains impurities.

[0085] <Second embodiment>

[0086] Next, a second embodiment of the liquefied carbon dioxide facility and the method for estimating the dry ice generation state according to the present invention will be described.

[0087] (Overall structure of liquefied carbon dioxide equipment)

[0088] Figure 6 This is a diagram showing a schematic configuration of a liquefied carbon dioxide plant according to a second embodiment of the present invention.

[0089] like Figure 6 As shown, the liquefied carbon dioxide plant 1B in this embodiment includes at least a tank 2, a pipe 10, a pressure sensor 20, a temperature sensor 30, a solid detector 50B, and a control device 60B.

[0090] The tank 2 can store liquefied carbon dioxide. The liquefied carbon dioxide stored in the tank 2 may also be mixed with impurities. In the following description, similarly to the first embodiment, the liquid containing the liquefied carbon dioxide and the impurities mixed in the liquefied carbon dioxide is referred to as the storage liquid L. The tank 2 is provided in the hull of a ship, the floating body of an offshore floating device, a liquefied gas storage facility on land, and the like.

[0091] The tank 2 is, for example, cylindrical. The tank 2 includes a cylindrical portion 3 and an end plate portion 4. The cylindrical portion 3 extends in a central axis direction Dc in which the central axis thereof extends. In this second embodiment, the central axis direction Dc is a direction perpendicular to the up-down direction Dv. The central axis direction Dc may be consistent with the horizontal direction, or may be slightly inclined relative to the horizontal direction. In this embodiment, the cylindrical portion 3 is formed in a cylindrical shape, and a cross-sectional shape perpendicular to the central axis direction Dc thereof is circular. The end plate portions 4 are respectively arranged at both ends of the cylindrical portion 3 in the central axis direction Dc. Each end plate portion 4 is hemispherical, closing the openings on both sides of the central axis direction Dc of the cylindrical portion 3.

[0092] The tank 2 may be arranged so that its central axis direction Dc coincides with the vertical direction Dv. The tank 2 is not limited to a cylindrical shape, but may be in other shapes such as a spherical shape or a square shape.

[0093] The liquefied carbon dioxide equipment 1B of the second embodiment includes, for example, a loading pipe 11 and a discharge pipe 12 as pipes 10. The loading pipe 11 and the discharge pipe 12 are connected to the tank 2, respectively. The loading pipe 11 and the discharge pipe 12 as pipes 10 can each allow the storage liquid L of liquefied carbon dioxide to flow. The pipe 10 may be any pipe connected to the tank 2, and is not limited to the loading pipe 11 and the discharge pipe 12, and may be a pipe for other purposes.

[0094] The loading pipe 11 is a pipe for loading the storage liquid L of liquefied carbon dioxide supplied from the outside into the tank 2. The loading pipe 11 passes through the top of the tank 2, for example, and extends from the upper side to the lower side in the vertical direction Dv inside and outside the tank 2. The front end of the loading pipe 11 (in other words, the lower end in the vertical direction Dv) opens downward at the lower part inside the tank 2.

[0095] The loading pipe 11 is provided with an on-off valve 15. The on-off valve 15 is disposed, for example, outside the tank 2. The on-off valve 15 opens and closes the loading pipe 11.

[0096] The discharge pipe 12 is a pipe for discharging the storage liquid L in the tank 2 to the outside of the tank 2. The discharge pipe 12 passes through the top of the tank 2 from the outside of the tank 2 and extends to the inside of the tank 2. The front end of the discharge pipe 12 is arranged at the lower part of the tank 2. A pump 13 is provided at the front end of the discharge pipe 12. The pump 13 is arranged in the tank 2. The pump 13 sucks the storage liquid L of liquefied carbon dioxide in the tank 2 and sends it to the outside of the tank 2 through the discharge pipe 12.

[0097] The discharge pipe 12 is provided with an on-off valve 16. The on-off valve 16 is disposed, for example, outside the tank 2. The on-off valve 16 opens and closes the discharge pipe 12.

[0098] The interior of the tank 2, the interior of the loading pipe 11, and the interior of the discharge pipe 12 are regions where liquefied carbon dioxide exists.

[0099] (Structure of pressure sensor and temperature sensor)

[0100] The pressure sensor 20 detects the pressure of the region where the liquefied carbon dioxide exists inside the tank 2 and inside the pipe 10. In the present embodiment, the pressure sensor 20 includes, for example, first to fifth pressure sensors 20A to 20E.

[0101] Among them, the first pressure sensor 20A, the second pressure sensor 20B, and the third pressure sensor 20C detect the pressure of each part in the tank 2. The first pressure sensor 20A detects the pressure of the upper part of the tank 2. The second pressure sensor 20B detects the pressure of the bottom part of the tank 2. The third pressure sensor 20C detects the pressure of the middle part of the tank 2 that is higher than the bottom. The number and configuration of the pressure sensors 20 provided in the tank 2 are not limited in any way. In addition to the first pressure sensor 20A, the second pressure sensor 20B, and the third pressure sensor 20C, other pressure sensors 20 may be provided. In addition, part of the first pressure sensor 20A, the second pressure sensor 20B, and the third pressure sensor 20C may be omitted.

[0102] Figure 2 It is a cross-sectional view showing a pressure sensor and a temperature sensor provided in the pipe according to the embodiment of the present invention.

[0103] like Figure 2 As shown, the fourth pressure sensor 20D and the fifth pressure sensor 20E detect the pressure of each part in the pipe 10. The fourth pressure sensor 20D and the fifth pressure sensor 20E are provided in each pipe of the loading pipe 11 and the discharge pipe 12. The fourth pressure sensor 20D detects the pressure near the pipe wall in the pipe 10. The fifth pressure sensor 20E detects the pressure of the middle part of the pipe 10 away from the pipe wall.

[0104] The number and arrangement of the pressure sensors provided in the pipe 10 are not limited, and in addition to the fourth pressure sensor 20D and the fifth pressure sensor 20E, other pressure sensors 20 may be provided. In addition, a plurality of sets of the fourth pressure sensor 20D and the fifth pressure sensor 20E may be provided at intervals in the extending direction of the pipe 10.

[0105] The temperature sensor 30 detects the temperature of the region where the liquefied carbon dioxide exists inside the tank 2 and the pipe 10. In the present embodiment, the temperature sensor 30 includes, for example, first to fifth temperature sensors 30A to 30E.

[0106] like Figure 6 As shown, the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C detect the temperature of the storage liquid L of the liquefied carbon dioxide at each part of the tank 2. The first temperature sensor 30A detects the temperature of the upper part of the tank 2. The second temperature sensor 30B detects the temperature of the bottom of the tank 2. The third temperature sensor 30C detects the temperature of the middle part above the bottom of the tank 2. As the first temperature sensor 30A and the second temperature sensor 30B, for example, a thermal camera or the like can be used. As the third temperature sensor 30C, for example, a thermocouple or the like can be used.

[0107] The number and arrangement of the temperature sensors 30 provided in the tank 2 are not limited in any way, and in addition to the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C, other temperature sensors 30 may be provided. In addition, a part of the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C may be omitted.

[0108] like Figure 2 As shown, the fourth temperature sensor 30D and the fifth temperature sensor 30E detect the temperature of each part in the pipe 10. The fourth temperature sensor 30D and the fifth temperature sensor 30E are provided in each pipe of the loading pipe 11 and the discharge pipe 12. The fourth temperature sensor 30D detects the pressure near the pipe wall of the pipe 10. The fifth temperature sensor 30E detects the temperature of the middle part of the pipe 10 away from the pipe wall. As the fourth temperature sensor 30D, for example, a thermal camera or the like can be used. As the fifth temperature sensor 30E, for example, a thermocouple or the like can be used.

[0109] The number and arrangement of the temperature sensors provided in the pipe 10 are not limited, and other temperature sensors 30 may be provided in addition to the fourth temperature sensor 30D and the fifth temperature sensor 30E. In addition, a plurality of sets of the fourth temperature sensor 30D and the fifth temperature sensor 30E may be provided at intervals in the extending direction of the pipe 10.

[0110] (Structure of Solid State Detection Section)

[0111] Figure 7 FIG. 1 is a diagram showing a solid detection unit according to a second embodiment of the present invention.

[0112] like Figure 7 As shown, the solid detector 50B detects the solid B mixed in the storage liquid L of the liquefied carbon dioxide in the area where the liquefied carbon dioxide exists in the pipe 10 from the outside. As the solid detector 50B, for example, a laser detection sensor, a microwave detection sensor, an electrostatic capacitance sensor, etc. can be used. For example, when a microwave detection sensor is used as the solid detector 50B, as shown in FIG. Figure 7 As shown, the solid detection unit 50B includes a pair of microwave horns 51A and 51B and a microwave generating device 52. The pair of microwave horns 51A and 51B face each other with the pipe 10 interposed therebetween.

[0113] The microwave generator 52 generates microwaves using a pair of microwave horns 51A and 51B. The solid detector 50B detects the granular solid B mixed in the storage liquid L of liquefied carbon dioxide in the pipe 10 based on the change of the generated microwave. The solid detector 50B detects the granular body formed by solidification of liquefied carbon dioxide and the granular body formed by solidification of impurities contained in the liquefied carbon dioxide in the storage liquid L of liquefied carbon dioxide as the solid B. In addition, the solid detector 50B can also detect the solid B mixed in the storage liquid L of liquefied carbon dioxide in the area where the liquefied carbon dioxide exists in the tank 2 from the outside of the tank 2.

[0114] (Hardware structure diagram)

[0115] Figure 3 It is a diagram showing the hardware configuration of the control device according to the embodiment of the present invention.

[0116] like Figure 3 As shown, the control device 60B is a computer including a CPU 61 (Central Processing Unit), a ROM 62 (Read Only Memory), a RAM 63 (Random Access Memory), a memory 64 such as a HDD (Hard Disk Drive), and a signal transceiver module 65 .

[0117] (Functional Block Diagram)

[0118] Figure 4 This is a functional block diagram of a control device according to an embodiment of the present invention.

[0119] like Figure 4 As shown, the CPU 61 of the control device 60B implements the functional components of the signal input unit 70 , the storage unit 71 , the estimation unit 72B, the control unit 73B, and the output unit 75 by executing a program pre-stored in the memory 64 or the like.

[0120] The signal input unit 70 receives detection signals from the pressure sensor 20 and the temperature sensor 30 via the signal transceiver module 65 .

[0121] The storage unit 71 stores information on the triple point based on the composition of the storage liquid L of liquefied carbon dioxide stored in the tank 2. The storage liquid L of liquefied carbon dioxide contains liquefied carbon dioxide and impurities mixed in the liquefied carbon dioxide. The pressure and temperature of the triple point of such storage liquid L are different from those of liquefied carbon dioxide that does not contain impurities. In addition, the pressure and temperature of the triple point are different depending on the amount of impurities in the storage liquid L relative to the liquefied carbon dioxide. Therefore, before the storage liquid L of liquefied carbon dioxide is stored in the tank 2, the composition of the storage liquid L is analyzed, and the information on the triple point including the pressure and temperature of the triple point of the storage liquid L is obtained in advance. The obtained triple point information is stored in the storage unit 71.

[0122] The estimation unit 72B estimates the state of dry ice generation in the region where liquefied carbon dioxide exists based on the detection results of the pressure sensor 20 and the temperature sensor 30 and whether the solid B is detected in the detection result of the solid detector 50B.

[0123] The estimation unit 72B obtains the detection result of the pressure sensor 20 (the first pressure sensor 20A to the fifth pressure sensor 20E) on the pressure of the stored liquid L in the region where the liquefied carbon dioxide exists in the tank 2 and the pipe 10, based on the detection signal from the pressure sensor 20 received by the signal input unit 70. The estimation unit 72B obtains the detection result of the temperature of the stored liquid L in the region where the liquefied carbon dioxide exists in each portion in the tank 2 and the pipe 10, based on the detection signal from the temperature sensor 30 received by the signal input unit 70.

[0124] The estimation unit 72B estimates the generation status of dry ice based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the triple point information stored in the storage unit 71. The estimation unit 72B compares the acquired pressure and temperature of the storage liquid L in the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the storage liquid L based on the information of the triple point of the storage liquid L stored in the storage unit 71. When the pressure of the storage liquid L in the region where the liquefied carbon dioxide exists is lower than the pressure of the triple point of the storage liquid L and the temperature of the storage liquid L in the region where the liquefied carbon dioxide exists is higher than the temperature of the triple point of the storage liquid L, the estimation unit 72B estimates that dry ice is generated in the storage liquid L in the region where the liquefied carbon dioxide exists.

[0125] When the solid B is detected in the storage liquid L of the liquefied carbon dioxide by the solid detection unit 50B, the estimation unit 72B estimates that the liquefied carbon dioxide or impurities contained in the liquefied carbon dioxide have solidified (solidified).

[0126] In the present embodiment, when the estimation unit 72B estimates that dry ice is being generated in the storage liquid L based on the detection results of the pressure and temperature of the region where liquefied carbon dioxide exists and solid B is detected in the storage liquid L, it estimates that dry ice is being generated in the region where liquefied carbon dioxide exists.

[0127] The control unit 73B controls the operations of the pump 13 and the on-off valves 15 and 16 to suppress the generation of dry ice based on the generation status of dry ice estimated by the estimating unit 72B.

[0128] When the estimating unit 72B estimates that dry ice is being generated, the control unit 73B, for example, stops the operation of the pump 13 to suppress the pressure drop in the tank 2. In addition, when the estimating unit 72B estimates that dry ice is being generated, the control unit 73B may, for example, increase the rotation speed of the pump 13 to pressurize the storage liquid L (liquefied carbon dioxide) in the pipe 10.

[0129] Furthermore, when the estimating unit 72B estimates that dry ice is being generated, the control unit 73B may close the on-off valves 15 and 16 to restore the static pressure in the pipe 10 .

[0130] The control unit 73B may control the operation of the pump 13 and the on-off valves 15 and 16 in whole or in part. In addition, the control unit 73B may control the operation of the pump 13 and the on-off valves 15 and 16 at the same time or at different times. In addition to the above, the control unit 73A may also supply pressurized fluid to the area where liquefied carbon dioxide exists.

[0131] (Steps of a method for estimating dry ice generation conditions)

[0132] Figure 8 This is a flowchart showing the steps of a method for estimating a dry ice generation state according to an embodiment of the present invention.

[0133] like Figure 8 As shown, the dry ice generation condition estimation method S20 of the embodiment of the present invention includes the following steps: a step S21 of detecting pressure and temperature; a step S22 of detecting the presence or absence of solid; a step S23 of estimating the dry ice generation condition; a step S24 of determining whether the condition is for dry ice generation; and a step S25 of controlling the operation of a pump and an opening and closing valve.

[0134] In step S21 of detecting pressure and temperature, the pressure and temperature of the area in which the liquefied carbon dioxide exists in the tank 2 and the pipe 10 are detected by the pressure sensor 20 and the temperature sensor 30. For this purpose, the first pressure sensor 20A, the second pressure sensor 20B, and the third pressure sensor 20C detect the pressure of each part in the tank 2. In addition, the fourth pressure sensor 20D and the fifth pressure sensor 20E detect the pressure of each part in the pipe 10. In addition, the first temperature sensor 30A, the second temperature sensor 30B, and the third temperature sensor 30C detect the temperature of each part in the tank 2. In addition, the fourth temperature sensor 30D and the fifth temperature sensor 30E detect the temperature of each part in the pipe 10.

[0135] Detection signals indicating detection results of the pressure sensor 20 and the temperature sensor 30 are transmitted to the control device 60B.

[0136] In step S22 of detecting the presence of solids, the solid detector 50B detects from the outside of the pipe 10 whether there is a solid B mixed in the liquefied carbon dioxide storage liquid L in the area where the liquefied carbon dioxide exists in the pipe 10. A detection signal indicating the detection result in the solid detector 50B is sent to the control device 60B.

[0137] In step S23 of estimating the generation state of dry ice, the generation state of dry ice in the region where liquefied carbon dioxide exists is estimated based on the detection results of the pressure and temperature in step S21 and the detection result of the solid B in step S22 .

[0138] To this end, the signal input unit 70 of the control device 60B receives the detection signals of the pressure sensor 20, the temperature sensor 30, and the solid detection unit 50B. Furthermore, the estimation unit 72B obtains the detection results of the pressure of the stored liquid L in each part of the tank 2 and the pipe 10 by the pressure sensor 20 (the first pressure sensor 20A to the fifth pressure sensor 20E) based on the detection signal from the pressure sensor 20 received by the signal input unit 70. In addition, the estimation unit 72B obtains the detection results of the temperature of the stored liquid L in each part of the tank 2 and the pipe 10 by the temperature sensor 30 (the first temperature sensor 30A to the fifth temperature sensor 30E) based on the detection signal from the temperature sensor 30 received by the signal input unit 70. Furthermore, the estimation unit 72B obtains the information of the triple point of the stored liquid L stored in the storage unit 71.

[0139] In step S23 of estimating the dry ice generation status, the estimation unit 72B further estimates the dry ice generation status based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the triple point information stored in the storage unit 71. For this purpose, the pressure and temperature of the storage liquid L in the region where the liquefied carbon dioxide exists obtained by the estimation unit 72B are compared with the pressure and temperature of the triple point of the storage liquid L based on the information of the triple point of the storage liquid L stored in the storage unit 71. Here, when the pressure of the storage liquid L in the region where the liquefied carbon dioxide exists is lower than the pressure of the triple point of the storage liquid L and the temperature of the storage liquid L in the region where the liquefied carbon dioxide exists is higher than the temperature of the triple point of the storage liquid L, the estimation unit 72B estimates that dry ice is generated in the storage liquid L in the region where the liquefied carbon dioxide exists.

[0140] The estimation unit 72B obtains a detection result indicating the presence or absence of the solid B mixed in the stored liquid L based on the detection signal from the solid detection unit 50B received by the signal input unit 70. When the solid detection unit 50B detects the presence of the solid B in the stored liquid L of liquefied carbon dioxide, the estimation unit 72B estimates that the liquefied carbon dioxide or impurities contained in the liquefied carbon dioxide are solidified and dry ice is generated in the stored liquid L.

[0141] In the present embodiment, when the estimation unit 72B estimates that dry ice is being generated in the storage liquid L based on the detection results of the pressure and temperature of the region where liquefied carbon dioxide exists and solid B is detected in the storage liquid L, it estimates that dry ice is being generated in the region where liquefied carbon dioxide exists.

[0142] In step S24 of determining whether the situation is such that dry ice is generated, it is determined in step S23 whether the situation is such that dry ice is generated in the storage liquid L in the area where liquefied carbon dioxide exists.

[0143] As a result of this determination, if it is determined that dry ice is not generated in the storage liquid L in the area where liquefied carbon dioxide exists (No in step S24), the process returns to step S21.

[0144] On the other hand, when it is determined that dry ice is generated in the storage liquid L in the area where liquefied carbon dioxide exists (YES in step S24 ), the process proceeds to step S25 .

[0145] In step S25 of controlling the operation of the pump and the on-off valve, if it is determined in step S24 that dry ice is generated in the storage liquid L, the operation of the pump 13 and the on-off valves 15 and 16 is controlled by the control unit 73B. For example, the control unit 73B stops the operation of the pump 13 to suppress the pressure drop in the tank 2. In addition, the control unit 73B may increase the rotation speed of the pump 13 to pressurize the storage liquid L (liquefied carbon dioxide) in the pipe 10. In addition, the control unit 73B closes the on-off valves 15 and 16 to restore the static pressure in the pipe 10. In this way, the growth of dry ice is suppressed and the generated dry ice is eliminated.

[0146] (Effect)

[0147] In the liquefied carbon dioxide equipment 1B of the above-mentioned embodiment, the pressure and temperature of the region where the liquefied carbon dioxide exists inside at least one of the tank 2 and the pipe 10 are detected by the pressure sensor 20 and the temperature sensor 30. Thus, even when the liquefied carbon dioxide contains impurities, the estimation unit 72B can compare the pressure and temperature of the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the liquefied carbon dioxide containing impurities based on the detection results of the pressure sensor 20 and the temperature sensor 30. Thus, the generation status of dry ice in the region where the liquefied carbon dioxide exists can be estimated with high accuracy. Therefore, even when the liquefied carbon dioxide contains impurities, the generation of dry ice can be effectively suppressed.

[0148] In addition, in the above-described embodiment, the storage unit 71 stores information on the triple point based on the composition of the storage liquid L stored in the tank 2. The estimating unit 72B estimates the generation status of dry ice based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the information on the triple point stored in the storage unit 71. Thus, the generation status of dry ice in the storage liquid L, which is liquefied carbon dioxide containing impurities, can be estimated with higher accuracy.

[0149] In addition, in the above-mentioned embodiment, the control unit 73B controls the operation of the pump 13 based on the dry ice generation condition estimated by the estimation unit 72B. Thus, when the estimation unit 72B estimates that dry ice is generated, it is possible to suppress the generation of dry ice and eliminate the generated dry ice by controlling the operation of the pump 13. As control of the operation of the pump 13, for example, there are stopping the operation of the pump 13 and pressurizing the liquid carbon dioxide by the pump 13.

[0150] Furthermore, in the above-described embodiment, when the estimating unit 72B estimates that dry ice is being generated, the generation of dry ice can be suppressed by closing the on-off valves 15 and 16 .

[0151] In addition, in the above-mentioned embodiment, the solid detection unit 50B detects the solid B mixed in the storage liquid L of the liquefied carbon dioxide in the area where the liquefied carbon dioxide exists. When the solid B is detected in the storage liquid L of the liquefied carbon dioxide, it can be assumed that the liquefied carbon dioxide or the impurities contained in the liquefied carbon dioxide are solidified. The estimation unit 72B can more effectively estimate the generation status of dry ice in the area where the liquefied carbon dioxide exists based on the pressure and temperature of the area where the liquefied carbon dioxide exists and whether the solid B is detected.

[0152] In addition, in the above-mentioned embodiment, when the solid detection unit 50B detects granular bodies formed by solidification of liquefied carbon dioxide and granular bodies formed by solidification of impurities contained in liquefied carbon dioxide as solid B, the estimation unit 72B can more effectively estimate the generation status of dry ice in the area where liquefied carbon dioxide exists.

[0153] In the dry ice generation state estimation method S20 of the above-mentioned embodiment, the dry ice generation state in the region where the liquefied carbon dioxide exists is estimated based on the detection results of the pressure and temperature of the region where the liquefied carbon dioxide exists. By comparing the detection results of the pressure and temperature of the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the liquefied carbon dioxide containing impurities, the generation of dry ice can be effectively suppressed even when the liquefied carbon dioxide contains impurities.

[0154] <Third embodiment>

[0155] Next, a third embodiment of the liquefied carbon dioxide equipment and the dry ice generation status estimation method of the present invention is described. In the third embodiment described below, the only difference from the second embodiment is that the pressure sensor 20 and the temperature sensor 30 are omitted, so the same parts as the second embodiment are marked with the same reference numerals and repeated descriptions are omitted.

[0156] (Overall structure of liquefied carbon dioxide equipment)

[0157] Fig. 9 This is a diagram showing a schematic configuration of a liquefied carbon dioxide plant according to a third embodiment of the present invention.

[0158] like Fig. 9 As shown, the liquefied carbon dioxide plant 1C in this embodiment includes at least a tank 2, a pipe 10, a solid detector 50B, and a control device 60C.

[0159] (Functional Block Diagram)

[0160] Fig. 9 This is a functional block diagram of a control device according to an embodiment of the present invention.

[0161] like Fig. 9 As shown, the CPU 61 of the control device 60C implements the functional components of the signal input unit 70 , the storage unit 71 , the estimation unit 72C, the control unit 73C, and the output unit 75 by executing a program pre-stored in the memory 64 or the like.

[0162] The estimating unit 72C estimates the state of dry ice generation in the region where liquefied carbon dioxide exists, based on whether or not the solid B is detected in the detection result of the solid detecting unit 50B.

[0163] When the solid B is detected in the storage liquid L of the liquefied carbon dioxide by the solid detection unit 50B, the estimation unit 72C estimates that the liquefied carbon dioxide or impurities contained in the liquefied carbon dioxide have solidified.

[0164] The control unit 73C controls the operation of the pump 13 and the on-off valves 15 and 16 based on the dry ice generation status estimated by the estimating unit 72C, similarly to the control unit 73B in the second embodiment.

[0165] (Steps of a method for estimating dry ice generation conditions)

[0166] Fig.11 This is a flowchart showing the steps of a method for estimating a dry ice generation state according to an embodiment of the present invention.

[0167] like Fig.11 As shown, the dry ice generation condition estimation method S30 of the embodiment of the present invention includes the following steps: a step S32 of detecting the presence or absence of solids; a step S33 of estimating the dry ice generation condition; a step S34 of determining whether the dry ice generation condition exists; and a step S35 of controlling the operation of a pump and an opening and closing valve.

[0168] In step S32 of detecting the presence of solids, the solid detector 50B detects from the outside of the pipe 10 whether there is solid B mixed in the liquefied carbon dioxide storage liquid L in the area where the liquefied carbon dioxide exists in the pipe 10. A detection signal indicating the detection result of the solid detector 50B is sent to the control device 60C.

[0169] In step S33 of estimating the generation status of dry ice, the generation status of dry ice in the region where liquefied carbon dioxide exists is estimated based on the detection result of the solid B in step S32.

[0170] For this purpose, the estimation unit 72C obtains a detection result indicating the presence or absence of the solid B mixed in the stored liquid L based on the detection signal from the solid detection unit 50B received by the signal input unit 70. When the presence of the solid B is detected in the stored liquid L of liquefied carbon dioxide by the solid detection unit 50B, the estimation unit 72C estimates that the liquefied carbon dioxide or impurities contained in the liquefied carbon dioxide are solidified and dry ice is generated in the stored liquid L.

[0171] In step S34 of determining whether the situation is such that dry ice is generated, it is determined whether the situation is such that dry ice is generated in the storage liquid L in the area where liquefied carbon dioxide exists in step S33.

[0172] As a result of this determination, if it is determined that dry ice is not generated in the storage liquid L in the area where liquefied carbon dioxide exists (No in step S34), the process returns to step S31.

[0173] On the other hand, when it is determined that dry ice is generated in the storage liquid L in the area where liquefied carbon dioxide exists (YES in step S34 ), the process proceeds to step S35 .

[0174] In step S35 of controlling the operation of the pump and the on-off valve, if it is determined in step S34 that dry ice is generated in the storage liquid L, the control unit 73C controls the operation of the pump 13 and the on-off valves 15 and 16. For example, the control unit 73C stops the operation of the pump 13 to suppress the pressure drop in the tank 2. In addition, the control unit 73C may increase the rotation speed of the pump 13 to pressurize the storage liquid L (liquefied carbon dioxide) in the pipe 10. In addition, the control unit 73C closes the on-off valves 15 and 16 to restore the static pressure in the pipe 10. In this way, the growth of dry ice is suppressed and the generated dry ice is eliminated.

[0175] (Effect)

[0176] In the liquefied carbon dioxide equipment 1C and the dry ice generation status estimation method S30 of the above-mentioned embodiment, the solid detection unit 50B detects the solid B mixed in the liquefied carbon dioxide storage liquid L in the area where the liquefied carbon dioxide exists, as in the above-mentioned second embodiment. When the solid B is detected in the liquefied carbon dioxide storage liquid L, it can be assumed that the liquefied carbon dioxide or the impurities contained in the liquefied carbon dioxide are solidified. The estimation unit 72C can more effectively estimate the dry ice generation status in the area where the liquefied carbon dioxide exists based on the pressure and temperature of the area where the liquefied carbon dioxide exists and whether the solid B is detected. Therefore, even if the liquefied carbon dioxide contains impurities, the generation of dry ice can be effectively suppressed.

[0177] In addition, in the above-mentioned embodiment, similar to the above-mentioned second embodiment, when the solid detection unit 50B detects granular bodies formed by solidification of liquefied carbon dioxide and granular bodies formed by solidification of impurities contained in liquefied carbon dioxide as solid B, the estimation unit 72C can more effectively estimate the generation status of dry ice in the area where liquefied carbon dioxide exists.

[0178] In addition, in the above-mentioned embodiment, the control unit 73C controls the operation of the pump 13 based on the dry ice generation condition estimated by the estimation unit 72C. Therefore, when the estimation unit 72C estimates that dry ice is generated, it is possible to perform processing such as suppressing the generation of dry ice and eliminating the generated dry ice by controlling the operation of the pump 13. As control of the operation of the pump 13, there are, for example, stopping the operation of the pump 13, pressurizing the liquid carbon dioxide by the pump 13, and the like.

[0179] Furthermore, in the above-described embodiment, when the estimating unit 72C estimates that the situation is one in which dry ice is generated, the generation of dry ice can be suppressed by closing the on-off valves 15 and 16 .

[0180] (Other embodiments)

[0181] As mentioned above, although the embodiment of the present invention is described in detail with reference to the drawings, the specific structure is not limited to this embodiment, and design changes and the like are also included within the scope that does not depart from the gist of the present invention.

[0182] Furthermore, in the above-described embodiment, the configurations of the liquefied carbon dioxide facilities 1A to 1C are shown, but the configurations of the various parts can be modified as appropriate.

[0183] In addition, in the above-mentioned embodiment, the steps S10, S20, and S30 of the dry ice generation state estimation method are shown, but the above-mentioned steps can be replaced in order as appropriate.

[0184] Furthermore, in the above-described embodiment, a case has been described where each functional configuration is realized by the control devices 60A to 60C executing a pre-stored program, but each function of the control devices 60A to 60C may be realized by hardware.

[0185] In addition, in the above-mentioned embodiment, the control unit 73A~73C is described as closing the on-off valves 15 and 16 when the estimation unit 72A~72C estimates that dry ice is generated. However, for example, in a case where the pressure in the piping 10 on the downstream side of the on-off valves 15 and 16 is increased, the on-off valves 15 and 16 can also be controlled to be open.

[0186] In addition, in the above-mentioned embodiment, the case where the solid B mixed in the storage liquid L of the liquefied carbon dioxide in the pipe 10 is detected by the solid detection units 50A and 50B is described. However, the solid B detected by the solid detection unit is not limited to the solid B in the pipe 10. For example, the solid B mixed in the storage liquid L of the liquefied carbon dioxide in the tank 2 may be detected by the solid detection unit.

[0187] <Note>

[0188] The liquefied carbon dioxide facilities 1A and 1B and the dry ice generation state estimation method S10 described in each embodiment can be understood as follows, for example.

[0189] (1) The liquefied carbon dioxide equipment 1A, 1B of the first embodiment comprises: a tank 2 capable of storing liquefied carbon dioxide; a pipe 10 connected to the tank 2 and capable of circulating the liquefied carbon dioxide; a pressure sensor 20 for detecting the pressure of a region where the liquefied carbon dioxide exists inside at least one of the tank 2 and the pipe 10; a temperature sensor 30 for detecting the temperature of the region where the liquefied carbon dioxide exists; and an estimating unit 72A, 72B for estimating the generation status of dry ice in the region where the liquefied carbon dioxide exists based on the detection results of the pressure sensor 20 and the temperature sensor 30.

[0190] The liquefied carbon dioxide equipment 1A, 1B detects the pressure and temperature of the region where the liquefied carbon dioxide exists inside at least one of the tank 2 and the pipe 10 by the pressure sensor 20 and the temperature sensor 30. Thus, even when the liquefied carbon dioxide contains impurities, the estimation units 72A, 72B can compare the pressure and temperature of the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the liquefied carbon dioxide containing impurities based on the detection results of the pressure sensor 20 and the temperature sensor 30. Thus, the generation of dry ice in the region where the liquefied carbon dioxide exists can be estimated with high accuracy. Therefore, even when the liquefied carbon dioxide contains impurities, the generation of dry ice can be effectively suppressed.

[0191] (2) The liquefied carbon dioxide equipment 1B of the second scheme is based on the liquefied carbon dioxide equipment 1B of (1), and further includes a solid detection unit 50B, the above-mentioned solid detection unit 50B detects the solid B mixed in the above-mentioned liquefied carbon dioxide in the area where the above-mentioned liquefied carbon dioxide exists from the outside of at least one of the above-mentioned tank 2 and the above-mentioned piping 10, and the above-mentioned estimation unit 72B estimates the generation status of dry ice based on the detection results of the above-mentioned pressure sensor 20 and the above-mentioned temperature sensor 30 and the detection result of the above-mentioned solid detection unit 50B.

[0192] In such a configuration, the solid detection unit 50B detects the solid B mixed in the liquefied carbon dioxide in the area where the liquefied carbon dioxide exists. When the solid B is detected in the liquefied carbon dioxide, it can be assumed that the liquefied carbon dioxide or impurities contained in the liquefied carbon dioxide have solidified. The estimation unit 72B can more effectively estimate the generation status of dry ice in the area where the liquefied carbon dioxide exists based on the pressure and temperature of the area where the liquefied carbon dioxide exists and whether the solid B is detected.

[0193] (3) The liquefied carbon dioxide equipment 1B of the third aspect is the liquefied carbon dioxide equipment 1B of (2), wherein the solid detection unit 50B detects, as the solid B, granular bodies formed by solidification of the liquefied carbon dioxide and granular bodies formed by solidification of impurities contained in the liquefied carbon dioxide.

[0194] Thus, when the solid detector 50B detects granular bodies formed by solidification of liquefied carbon dioxide and granular bodies formed by solidification of impurities contained in liquefied carbon dioxide as solid B, the estimating unit 72B can more effectively estimate the generation status of dry ice in the area where liquefied carbon dioxide exists.

[0195] (4) The liquefied carbon dioxide equipment 1A, 1B of the fourth aspect is the liquefied carbon dioxide equipment 1A, 1B of any one of (1) to (3), wherein the liquefied carbon dioxide equipment 1A, 1B further includes a storage unit 71, the storage unit 71 storing information on a triple point based on the composition of a storage liquid L, the storage liquid L containing the liquefied carbon dioxide stored in the tank 2 and impurities mixed in the liquefied carbon dioxide, and the estimating unit 72A, 72B estimates the dry ice generation status based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the information on the triple point stored in the storage unit 71.

[0196] In such a configuration, the storage unit 71 stores information on the triple point based on the composition of the storage liquid L stored in the tank 2. The estimating units 72A and 72B estimate the generation status of dry ice based on the detection results of the pressure sensor 20 and the temperature sensor 30 and the information on the triple point stored in the storage unit 71. Thus, the generation status of dry ice in the storage liquid L, which is liquefied carbon dioxide containing impurities, can be estimated with higher accuracy.

[0197] (5) The liquefied carbon dioxide equipment 1A, 1B of the fifth scheme is based on any one of the liquefied carbon dioxide equipment 1A, 1B in (1) to (4), and further includes a control unit 73A, 73B, and the above-mentioned control unit 73A, 73B controls the operation of the pump 13 provided in the above-mentioned tank based on the above-mentioned dry ice generation status estimated by the above-mentioned estimation unit 72A, 72B.

[0198] Thus, the control units 73A and 73B control the operation of the pump 13 based on the dry ice generation conditions estimated by the estimating units 72A and 72B. Thus, when the estimating units 72A and 72B estimate that dry ice is generated, it is possible to suppress the generation of dry ice and eliminate the generated dry ice by controlling the operation of the pump 13. Examples of the control of the operation of the pump 13 include stopping the operation of the pump 13 and pressurizing the liquid carbon dioxide by the pump 13.

[0199] (6) The liquefied carbon dioxide equipment 1A, 1B of the sixth scheme is based on any one of the liquefied carbon dioxide equipment 1A, 1B in (1) to (5), and the liquefied carbon dioxide equipment 1A, 1B has the on-off valves 15, 16 for opening and closing the above-mentioned piping 10, and the above-mentioned control unit 73A, 73B closes the above-mentioned on-off valves 15, 16 when the above-mentioned estimation unit 72A, 72B estimates that the above-mentioned dry ice is generated.

[0200] Thus, when the estimating units 72A and 72B estimate that dry ice is being generated, the generation of dry ice can be suppressed by closing the on-off valves 15 and 16 .

[0201] (7) The liquefied carbon dioxide equipment 1B, 1C of the seventh scheme comprises: a tank 2 capable of storing liquefied carbon dioxide; a piping 10 connected to the tank 2 and capable of circulating the liquefied carbon dioxide; a solid detection unit 50B for detecting solid B mixed in the liquefied carbon dioxide in an area where the liquefied carbon dioxide exists inside at least one of the tank 2 and the piping 10; and an estimating unit 72B, 72C for estimating the generation status of dry ice in the area where the liquefied carbon dioxide exists based on the detection status of the solid B by the solid detection unit 50B.

[0202] Thus, the solid detection unit 50B detects the solid B mixed in the liquefied carbon dioxide in the area where the liquefied carbon dioxide exists. The estimation units 72B and 72C estimate the generation status of dry ice in the area where the liquefied carbon dioxide exists based on whether the solid B is detected. Thus, when the solid B is detected in the liquefied carbon dioxide, it can be estimated that the liquefied carbon dioxide or the impurities contained in the liquefied carbon dioxide are solidified. Therefore, even when the liquefied carbon dioxide contains impurities, the generation of dry ice can be effectively suppressed.

[0203] (8) The liquefied carbon dioxide equipment 1B and 1C of the eighth embodiment is the liquefied carbon dioxide equipment 1B and 1C of (7), wherein the solid detection unit 50B detects granular matter formed by solidification of the liquefied carbon dioxide and impurities contained in the liquefied carbon dioxide as the solid B in the liquefied carbon dioxide.

[0204] Thus, when the solid detector 50B detects granular bodies formed by solidification of liquefied carbon dioxide and granular bodies formed by solidification of impurities contained in liquefied carbon dioxide as solid B, the estimator 72A can estimate that dry ice may be generated in the region where liquefied carbon dioxide exists.

[0205] (9) The liquefied carbon dioxide equipment 1B, 1C of the ninth scheme is based on the liquefied carbon dioxide equipment 1A of (7) or (8), and the liquefied carbon dioxide equipment further includes a control unit 73B, 73C, and the above-mentioned control unit 73B, 73C controls the operation of the pump 13 provided in the above-mentioned tank based on the detection status of the above-mentioned solid B by the above-mentioned solid detection unit 50B.

[0206] Thus, the control units 73B and 73C control the operation of the pump 13 based on the dry ice generation conditions estimated by the estimating units 72B and 72C. Thus, when the estimating units 72B and 72C estimate that dry ice is generated, it is possible to suppress the generation of dry ice and eliminate the generated dry ice by controlling the operation of the pump 13. Examples of the control of the operation of the pump 13 include stopping the operation of the pump 13 and pressurizing the liquid carbon dioxide by the pump 13.

[0207] (10) The liquefied carbon dioxide equipment 1B, 1C of the tenth scheme is based on the liquefied carbon dioxide equipment 1B, 1C of (9), and the liquefied carbon dioxide equipment 1B, 1C has on-off valves 15, 16 for opening and closing the above-mentioned piping 10. When the above-mentioned solid B is detected, the above-mentioned estimation unit 72B, 72C estimates that the above-mentioned dry ice is being generated, and the above-mentioned control unit 73B, 73C closes the above-mentioned on-off valves 15, 16.

[0208] Thus, when the estimating units 72B and 72C estimate that dry ice is being generated, the generation of dry ice can be suppressed by closing the on-off valves 15 and 16 .

[0209] (11) The dry ice generation status estimation method S10, S20 of the eleventh scheme is the dry ice generation status estimation method S10, S20 in any one of the liquefied carbon dioxide equipment 1A, 1B in (1) to (6), comprising the following steps: steps S11, S21 of detecting the pressure and temperature of the area where the above-mentioned liquefied carbon dioxide exists; and steps S12, S23 of estimating the dry ice generation status in the area where the above-mentioned liquefied carbon dioxide exists based on the detection results of the above-mentioned pressure and the above-mentioned temperature.

[0210] The dry ice generation status estimation method S10, S20 can estimate the dry ice generation status in the region where the liquefied carbon dioxide exists based on the pressure and temperature detection results of the region where the liquefied carbon dioxide exists. By comparing the pressure and temperature detection results of the region where the liquefied carbon dioxide exists with the pressure and temperature of the triple point of the liquefied carbon dioxide containing impurities, the generation of dry ice can be effectively suppressed even when the liquefied carbon dioxide contains impurities.

[0211] (12) The dry ice generation status estimation method S20, S30 of the twelfth scheme is the dry ice generation status estimation method S20, S30 in any one of the liquefied carbon dioxide equipment 1B, 1C in (7) to (10), comprising the following steps: steps S22, S32 of detecting whether there is a solid B mixed in the liquefied carbon dioxide in the area where the liquefied carbon dioxide exists; and steps S23, S33 of estimating the dry ice generation status in the area where the liquefied carbon dioxide exists based on the detection result of the solid B.

[0212] The dry ice generation status estimation method S20, S30 detects whether there is solid B mixed in liquefied carbon dioxide in the area where liquefied carbon dioxide exists, and estimates the dry ice generation status in the area where liquefied carbon dioxide exists based on the seven detection results. When solid B is detected in liquefied carbon dioxide, it can be estimated that liquefied carbon dioxide or impurities contained in liquefied carbon dioxide have solidified. Therefore, even if impurities are contained in liquefied carbon dioxide, the generation of dry ice can be effectively suppressed.

[0213] Industrial Applicability

[0214] According to the liquefied carbon dioxide equipment and the dry ice generation state estimation method of the present invention, even when impurities are contained in the liquefied carbon dioxide, the generation of dry ice can be effectively suppressed.

[0215] Description of Reference Numerals

[0216] 1A~1C…liquefied carbon dioxide equipment; 2…tank; 3…cylindrical part; 4…end plate; 10…pipe; 11…loading pipe; 12…discharging pipe; 13…pump; 15, 16…opening and closing valve; 20…pressure sensor; 20A…first pressure sensor; 20B…second pressure sensor; 20C…third pressure sensor; 20D…fourth pressure sensor; 20E…fifth pressure sensor; 30…temperature sensor; 30A…first temperature sensor; 30B…second temperature sensor; 30C…third temperature sensor; 30D…fourth temperature sensor; 30E…fifth temperature sensor; 50B…solid detection part; 51A, 51B…microwave horn; 52…microwave generating device; 60A~60C…control device 61…CPU; 62…ROM; 63…RAM; 64…memory; 65…signal transceiver module; 70…signal input unit; 71…storage unit; 72A~72C…estimation unit; 73A~73C…control unit; 75…output unit; B…solid; Dc…central axis direction; Dv…up and down direction; L…storage liquid; S10, S20, S30…dry ice generation condition estimation method; S11, S21…pressure and temperature detection step; S12, S23, S33…step of estimating dry ice generation condition; S13, S24, S34…step of determining whether dry ice generation condition exists; S14, S25, S35…step of controlling pump and opening and closing valve; S22…step of detecting the presence of solid.

Claims

1. A liquefied carbon dioxide device, comprising: Tanks capable of storing liquefied carbon dioxide; a pipe connected to the tank and capable of allowing the liquefied carbon dioxide to flow; a pressure sensor for detecting a pressure of a region where the liquefied carbon dioxide exists inside at least one of the tank and the pipe; a temperature sensor for detecting a temperature of a region where the liquefied carbon dioxide exists; and The estimating unit estimates the generation status of dry ice in the region where the liquefied carbon dioxide exists based on the detection results of the pressure sensor and the temperature sensor.

2. The liquefied carbon dioxide equipment according to claim 1, wherein: The liquefied carbon dioxide equipment further includes a solid detector configured to detect solids mixed in the liquefied carbon dioxide in a region where the liquefied carbon dioxide exists from outside at least one of the tank and the pipe. The estimating unit estimates a generation status of dry ice based on detection results of the pressure sensor and the temperature sensor and a detection result of the solid detector.

3. The liquefied carbon dioxide equipment according to claim 2, wherein: The solid detection unit detects, in the liquefied carbon dioxide, granular bodies formed by solidification of the liquefied carbon dioxide and granular bodies formed by solidification of impurities contained in the liquefied carbon dioxide as the solids.

4. The liquefied carbon dioxide equipment according to claim 1 or 2, wherein: The liquefied carbon dioxide equipment further includes a storage unit that stores information on a triple point based on a composition of a storage liquid, the storage liquid containing the liquefied carbon dioxide stored in the tank and impurities mixed in the liquefied carbon dioxide. The estimating unit estimates a generation status of dry ice based on detection results of the pressure sensor and the temperature sensor and the information of the triple point stored in the storage unit.

5. The liquefied carbon dioxide equipment according to claim 1 or 2, wherein: The liquefied carbon dioxide equipment further includes a control unit configured to control an operation of a pump provided in the tank based on the dry ice generation status estimated by the estimating unit.

6. The liquefied carbon dioxide equipment according to claim 5, wherein: The liquefied carbon dioxide equipment includes an on-off valve for opening and closing the pipe. The control unit closes the on-off valve when the estimating unit estimates that the dry ice is being generated.

7. A liquefied carbon dioxide device comprising: Tanks capable of storing liquefied carbon dioxide; a pipe connected to the tank and capable of allowing the liquefied carbon dioxide to flow; a solid detection unit that detects solids mixed in the liquefied carbon dioxide in a region where the liquefied carbon dioxide exists inside at least one of the tank and the pipe; and The estimating unit estimates a generation status of dry ice in a region where the liquefied carbon dioxide exists, based on a detection status of the solid by the solid detecting unit.

8. The liquefied carbon dioxide equipment according to claim 7, wherein: The solid detection unit detects, in the liquefied carbon dioxide, granular bodies in which impurities contained in the liquefied carbon dioxide are solidified as the solid.

9. The liquefied carbon dioxide equipment according to claim 7 or 8, wherein: The liquefied carbon dioxide equipment further includes a control unit configured to control an operation of a pump provided in the tank based on a detection condition of the solid by the solid detector.

10. The liquefied carbon dioxide equipment according to claim 9, wherein: The liquefied carbon dioxide equipment includes an on-off valve for opening and closing the pipe. When the solid is detected, the estimating unit estimates that the dry ice is being generated, and the control unit closes the on-off valve.

11. A method for estimating dry ice generation conditions, the method for estimating dry ice generation conditions in the liquefied carbon dioxide equipment according to claim 1 or 2, The method for estimating the generation status of dry ice comprises the following steps: a step of detecting the pressure and temperature of the region where the liquefied carbon dioxide exists; and A step of estimating a state of dry ice generation in a region where the liquefied carbon dioxide exists based on the detection results of the pressure and the temperature.

12. A method for estimating dry ice generation conditions, the method for estimating dry ice generation conditions in the liquefied carbon dioxide equipment according to claim 7 or 8, The method for estimating the generation status of dry ice comprises the following steps: a step of detecting whether there is a solid mixed in the liquefied carbon dioxide in an area where the liquefied carbon dioxide exists; and A step of estimating a state of dry ice generation in a region where the liquefied carbon dioxide exists based on the solid detection result.

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