WO2023204052A1 - Floating body and carbon dioxide recovery method - Google Patents

Abstract

This floating body is provided with: a combustion device that operates using a liquefied flammable gas as a fuel and discharges an exhaust gas; a liquefied flammable gas storage unit in which the liquefied flammable gas is stored; a fuel supply line through which the liquefied flammable gas is supplied to the combustion device from the liquefied flammable gas storage unit; a carbon dioxide recovery device equipped with an absorption column in which carbon dioxide contained in the exhaust gas is absorbed in an absorption solution and a regeneration column in which carbon dioxide in a gaseous form is separated from the absorption solution in which carbon dioxide has been absorbed in the absorption column; a carbon dioxide liquefaction device for liquefying carbon dioxide discharged from the carbon dioxide recovery device using, as a cooling heat source, the liquefied flammable gas supplied to the combustion device from the liquefied flammable gas storage unit through the fuel supply line; and a liquefied carbon dioxide storage unit in which carbon dioxide that has been liquefied by the carbon dioxide liquefaction device is stored.

Description

Floating body and carbon dioxide recovery method

The present disclosure relates to a floating body and a carbon dioxide recovery method.
This application claims priority to Japanese Patent Application No. 2022-068232 filed in Japan on April 18, 2022, the contents of which are incorporated herein.

In floating bodies such as ships, there is a need to reduce nitrogen oxides in exhaust gas emitted from engines, etc. For example, Patent Document 1 states that some of the fuel for combustion devices such as main engines and generators is reduced. As such, a technology has been proposed that uses boil-off gas of liquefied combustible gas such as liquefied natural gas stored in cargo tanks. Furthermore, in order to reduce carbon dioxide emissions, Patent Document 1 describes a technology that separates carbon dioxide contained in exhaust gas and refrigerates it as liquid carbon dioxide or solid carbon dioxide using the cold energy of liquefied natural gas. is proposed.

Japanese Patent Application Publication No. 2011-245995

In a ship like the one described in Patent Document 1, energy is required to separate and liquefy carbon dioxide from exhaust gas, but in order to generate such energy on a floating body, an engine etc. must be driven. This is necessary and carbon dioxide is emitted. Therefore, it is desired to reduce the energy required to separate and liquefy carbon dioxide from exhaust gas.
The present disclosure has been made in view of the above circumstances, and provides a floating body and carbon dioxide that can efficiently recover carbon dioxide by suppressing the energy required to separate and liquefy carbon dioxide from exhaust gas. It provides a collection method.

In order to solve the above problems, the following configuration is adopted.
According to a first aspect of the present disclosure, the floating body includes a combustion device that operates using liquefied combustible gas as fuel and discharges exhaust gas, a liquefied combustible gas storage section that stores the liquefied combustible gas, and a liquefied combustible gas a fuel supply line that supplies the liquefied combustible gas from the gas storage section to the combustion device; an absorption tower that absorbs carbon dioxide contained in the exhaust gas into an absorption liquid; and an absorption tower that absorbs the carbon dioxide. a carbon dioxide recovery device having a regeneration tower that separates gaseous carbon dioxide from the absorbed liquid; The carbon dioxide liquefaction device includes a carbon dioxide liquefaction device that liquefies carbon dioxide discharged from the carbon dioxide recovery device as a source, and a liquefied carbon dioxide storage section that stores the carbon dioxide liquefied by the carbon dioxide liquefaction device.

According to a second aspect of the present disclosure, the carbon dioxide recovery method is a carbon dioxide recovery method for recovering carbon dioxide from exhaust gas discharged by burning a liquefied combustible gas, the carbon dioxide contained in the exhaust gas. a step of separating gaseous carbon dioxide from the absorbing liquid that has absorbed the carbon dioxide; and a step of separating gaseous carbon dioxide from the absorbing liquid using the liquefied flammable gas as a cold heat source. The method includes a step of liquefying the carbon dioxide, and a step of storing the liquefied carbon dioxide.

According to the floating body and carbon dioxide recovery method according to the present disclosure, it is possible to efficiently recover carbon dioxide by suppressing the energy required to separate and liquefy carbon dioxide from exhaust gas.

FIG. 1 is a configuration diagram showing a schematic configuration of a floating body according to an embodiment of the present disclosure. It is a flow chart of a carbon dioxide recovery method in a first embodiment of the present disclosure. 1 is a diagram showing a schematic configuration of a carbon dioxide recovery system provided in a floating body according to a first embodiment of the present disclosure. It is a diagram showing a schematic configuration of a carbon dioxide recovery system provided in a floating body in a second embodiment of the present disclosure. It is a figure showing a schematic structure of a carbon dioxide recovery system provided in a floating body in a third embodiment of the present disclosure. It is a figure showing a schematic structure of a carbon dioxide recovery system provided in a floating body in a fourth embodiment of the present disclosure.

《First embodiment》
Next, a floating body and a carbon dioxide recovery method in the first embodiment of the present disclosure will be described based on the drawings.
FIG. 1 is a configuration diagram showing a schematic configuration of a floating body of this embodiment.
(Ship configuration)
As shown in FIG. 1, in this embodiment, the floating body 1A includes a floating body main body 2, a combustion device 9, a carbon dioxide recovery system 10A (see FIG. 3), a liquefied carbon dioxide storage section 11, and a liquefied combustible gas. It includes at least a storage section 21, a fuel supply line 22, and a vaporizer 23. The floating body 1A of the present embodiment will be described as an example of a ship that can be navigated by a main engine, but is not limited to a ship as long as it is a floating body that is equipped with at least a combustion device 9 that uses liquefied combustible gas F as fuel. When the floating body 1A is a ship, the type of ship is not limited to a specific ship type, and examples thereof include a liquefied gas carrier, a ferry, a RORO ship, a car carrier, and a passenger ship. Examples of the floating body 1A that is not a ship include FSU (Floating Storage Unit), FSRU (Floating Storage and Regasification Unit), and the like.

(Composition of floating body)
The floating body 2 has a pair of sides 3A and 3B forming its outer shell, a bottom (not shown), and an upper deck 5. The sides 3A and 3B have a pair of side skins forming port and starboard sides, respectively. The bottom of the ship has a bottom shell plate that connects these sides 3A and 3B. The outer shell of the floating body 2 has a U-shape in a cross section perpendicular to the bow and stern direction Da due to the pair of sides 3A, 3B and the bottom. The upper deck 5 illustrated in this embodiment is a full deck exposed to the outside. An upper structure 7 having a living area is formed on the upper deck 5 on the stern 2b side of the floating body 2. Further, in the floating body body 2 illustrated in this embodiment, a cargo loading section 8 (in other words, a cargo hold) is formed closer to the bow 2a than the upper structure 7. Note that the positions of the superstructure 7 and the cargo loading section 8 are merely examples; for example, the superstructure 7 may be arranged on the bow 2a side of the floating body 2, and the cargo loading section 8 may be arranged on the stern 2b side.

The combustion device 9 is arranged within the floating body body 2. The combustion device 9 exhibits a required function by burning the liquefied combustible gas F. Examples of the combustion device 9 include a main engine, a generator, and a boiler. The main engine is an engine (internal combustion engine) that uses liquefied combustible gas F as fuel, and exerts propulsive force for propelling the floating body body 2. The generator includes an engine (internal combustion engine) that uses liquefied combustible gas F as fuel, and generates electric power used within the floating body body 2 by the driving force of the engine. The boiler generates steam used within the floating body body 2 by burning the liquefied combustible gas F.

FIG. 3 is a diagram showing a schematic configuration of a carbon dioxide recovery system provided in a floating body according to the first embodiment of the present disclosure.
As shown in FIGS. 1 and 3, the liquefied carbon dioxide storage section 11 is a tank that stores liquefied carbon dioxide recovered by the carbon dioxide recovery system 10A. In other words, the liquefied carbon dioxide storage section 11 is configured to be able to store carbon dioxide in a liquid state.

The liquefied combustible gas storage section 21 stores liquefied combustible gas F. The liquefied combustible gas F of this embodiment is a fuel used in the floating body 1A, and is burned in the combustion device 9. That is, the liquefied combustible gas storage section 21 is a fuel tank for storing fuel. The liquid phase of the liquefied combustible gas F stored in the liquefied combustible gas storage section 21 has a lower temperature than the liquid phase of carbon dioxide C stored in the liquefied carbon dioxide storage section 11 . Examples of the liquefied combustible gas F include liquefied natural gas (LNG), methane, and ethane. In this embodiment, a case where liquefied natural gas is used as the liquefied combustible gas F will be described as an example.

The fuel supply line 22 supplies the liquefied combustible gas F from the liquefied combustible gas storage section 21 to the combustion device 9 .
The vaporizer 23 is provided in the middle of the fuel supply line 22 and vaporizes the liquefied combustible gas F. Combustible gas G obtained by vaporizing the liquefied combustible gas F is introduced into the combustion device 9 and burned.

The carbon dioxide recovery system 10A recovers carbon dioxide contained in the exhaust gas E of the combustion device 9 and liquefies it. The carbon dioxide recovery system 10A includes a carbon dioxide recovery device 31, a carbon dioxide liquefaction device 32, and a liquefied carbon dioxide storage section 11.
The carbon dioxide recovery device 31 recovers carbon dioxide from the exhaust gas E discharged from the combustion device 9. The carbon dioxide recovery device 31 includes an exhaust gas cooling tower 34, an absorption tower 35, and a regeneration tower 36.

The exhaust gas cooling tower 34 cools the exhaust gas E discharged from the combustion device 9. The exhaust gas cooling tower 34 in this embodiment stores the exhaust gas E discharged from the combustion device 9 in seawater around the floating body 2 or in a fresh water tank (not shown) provided in the floating body 2. It is cooled (for example, cooled to about 40 degrees Celsius) using fresh water as a cold heat source. Note that the exhaust gas cooling tower 34 may be provided as necessary, and may be omitted, for example, when the temperature of the exhaust gas introduced into the absorption tower 35 is sufficiently lowered.

The absorption tower 35 causes an absorption liquid (not shown) to absorb carbon dioxide contained in the exhaust gas E. For example, the absorption tower 35 causes the absorption liquid to fall from the upper part of the absorption tower 35, and contacts the exhaust gas E introduced into the absorption tower 35, thereby causing the absorption liquid to absorb carbon dioxide contained in the exhaust gas E. The exhaust gas E after carbon dioxide has been absorbed into the absorption liquid is discharged from the top of the absorption tower 35 and introduced into the exhaust gas cleaning tower 38 . The exhaust gas cleaning tower 38 causes clean water to fall from the upper part of the exhaust gas cleaning tower 38 to wash away the absorption liquid contained in the exhaust gas E that has exited the absorption tower 35 . The exhaust gas E exiting the exhaust gas cleaning tower 38 is led to, for example, an exhaust funnel (not shown) provided on the floating body 1A, and is released into the atmosphere. Examples of liquids for absorbing carbon dioxide by chemical absorption include MEA (monoethanolamine).

The regeneration tower 36 separates gaseous carbon dioxide from the absorption liquid that has absorbed carbon dioxide in the absorption tower 35. More specifically, the regeneration tower 36 heats the absorption liquid sent into the regeneration tower 36 from the lower part of the absorption tower 35 using steam generated in a boiler (not shown) provided in the floating body body 2. do. As a result, gaseous carbon dioxide is separated from the absorption liquid in the regeneration tower 36 , and the separated gaseous carbon dioxide is introduced into the carbon dioxide liquefaction device 32 via the gaseous carbon dioxide introduction line 37 . On the other hand, the absorption liquid from which gaseous carbon dioxide has been separated and regenerated is returned to the absorption tower 35 and reused.

The carbon dioxide liquefaction device 32 liquefies gaseous carbon dioxide discharged from the carbon dioxide recovery device 31. The carbon dioxide liquefier 32 includes a compressor 41 that compresses gaseous carbon dioxide, and a liquefier 42 that liquefies the gaseous carbon dioxide compressed by the compressor 41. The carbon dioxide liquefaction device 32 of this embodiment uses the liquefied combustible gas F supplied from the liquefied combustible gas storage section 21 to the combustion device 9 via the fuel supply line 22 as a cold source used in the liquefier 42. . That is, the liquefier 42 is provided in the middle of the fuel supply line 22. The carbon dioxide liquefied by the liquefier 42 is introduced into the liquefied carbon dioxide storage section 11 via the liquefied carbon dioxide discharge line 43 and is stored therein.

Here, the temperature of the liquefied combustible gas F after being used as a cold heat source in the liquefier 42 rises higher than the liquid phase of the liquefied combustible gas F stored in the liquefied combustible gas storage section 21, but it is still a liquid phase. The state includes. The above-mentioned vaporizer 23 is provided in the fuel supply line 22 closer to the combustion device 9 than the liquefier 42, and heats the liquefied combustible gas F after being used as a cold heat source. It is vaporized. The vaporizer 23 of this embodiment heats the liquefied combustible gas F using a heat medium such as steam from the boiler described above, for example.

(Carbon dioxide recovery method)
Next, a carbon dioxide recovery method in an embodiment of the present disclosure will be described with reference to the drawings. FIG. 2 is a flowchart of the carbon dioxide recovery method in the first embodiment of the present disclosure.
First, as shown in FIG. 2, carbon dioxide contained in the exhaust gas E is absorbed into an absorption liquid (step S01). In this embodiment, exhaust gas E discharged from a combustion device operating using liquefied combustible gas F as fuel is introduced into the absorption tower 35. Then, the gaseous carbon dioxide contained in the exhaust gas E is absorbed into the absorption liquid using the absorption tower 35.

Next, gaseous carbon dioxide is separated from the absorption liquid in which carbon dioxide has been absorbed (step S02). In this embodiment, the absorption liquid that has absorbed carbon dioxide is introduced into the regeneration tower 36 to separate gaseous carbon dioxide from the absorption liquid.
Further, the gaseous carbon dioxide separated from the absorption liquid is liquefied using the liquefied combustible gas as a cold heat source (step S03). In this embodiment, gaseous carbon dioxide is compressed by the compressor 41, and the compressed gaseous carbon dioxide is introduced into the liquefier 42. Then, the liquefier 42 exchanges heat with the liquefied combustible gas F, which is supplied as fuel from the liquefied combustible gas storage section 21 to the combustion device 9 via the fuel supply line 22, to liquefy the gaseous carbon dioxide.
After that, the liquefied carbon dioxide is stored (step S04). In this embodiment, carbon dioxide liquefied by the liquefier 42 is stored in the liquefied carbon dioxide storage section 11 via the liquefied carbon dioxide discharge line 43.

(effect)
According to the first embodiment, gaseous carbon dioxide contained in the exhaust gas E discharged from the floating body body 2 can be efficiently separated by the absorption tower 35 and the regeneration tower 36 of the carbon dioxide recovery device 31. . Therefore, the energy required to separate and liquefy carbon dioxide from the exhaust gas E can be suppressed, and carbon dioxide can be efficiently recovered.
Furthermore, since the volume of carbon dioxide can be reduced by liquefying the carbon dioxide separated by the carbon dioxide recovery device 31 in the carbon dioxide liquefaction device 32, the size of the container for storing the recovered carbon dioxide can be avoided. It can be suppressed.

According to the first embodiment, the liquefied combustible gas F used as a cold source for the carbon dioxide liquefaction device 32 is further introduced into the vaporization device 23. Thereby, the liquefied combustible gas F, which is the fuel for the combustion device 9, can be heated before being introduced into the vaporization device 23. Therefore, the energy required to vaporize the liquefied combustible gas F in the vaporizer 23 can be reduced, making it possible to recover carbon dioxide even more efficiently.

《Second embodiment》
Next, a second embodiment of the floating body according to the present disclosure will be described. In the second embodiment described below, the configuration of the fuel supply system including the fuel supply line 22 differs from the first embodiment. Therefore, while referring to FIG. 1 and giving the same reference numerals to the same parts as those in the first embodiment, the explanation will be omitted, and redundant explanation will be omitted.

FIG. 4 is a diagram showing a schematic configuration of a carbon dioxide recovery system provided in a floating body in a second embodiment of the present disclosure.
Similar to the floating body 1A of the first embodiment, the floating body 1B in the second embodiment includes a floating body main body 2, a combustion device 9, a carbon dioxide recovery system 10B (see FIG. 4), a liquefied carbon dioxide storage section 11, It includes at least a liquefied combustible gas storage section 21, a fuel supply line 22, and a vaporizer 23.

The carbon dioxide recovery system 10B of this second embodiment recovers and liquefies carbon dioxide contained in the exhaust gas E of the combustion device 9. As shown in FIG. 4, the carbon dioxide recovery system 10B includes a carbon dioxide recovery device 31, a carbon dioxide liquefaction device 32, and a liquefied carbon dioxide storage section 11.
The carbon dioxide recovery device 31 recovers carbon dioxide from the exhaust gas E discharged from the combustion device 9. The carbon dioxide recovery device 31 includes an exhaust gas cooling tower 34, an absorption tower 35, and a regeneration tower 36.

The exhaust gas cooling tower 134 cools the exhaust gas E discharged from the combustion device 9, similar to the exhaust gas cooling tower 34 of the first embodiment. The exhaust gas cooling tower 134 in this second embodiment uses the liquefied combustible gas F used as a cold source by the carbon dioxide liquefaction device 32 as a cold source to cool the exhaust gas E discharged from the combustion device 9 (e.g. (cool down to a certain degree). The exhaust gas E cooled by the exhaust gas cooling tower 134 is introduced into the absorption tower 35. Then, the carbon dioxide absorbed into the absorption liquid in the absorption tower 35 is heated in the regeneration tower 36, separated from the absorption liquid, and introduced into the carbon dioxide liquefaction device 32.

The carbon dioxide liquefaction device 32 includes a compressor 41 and a liquefier 42 as in the first embodiment, and the liquefied combustible gas storage section 21 is connected to the liquefied combustible gas storage section 21 by the fuel supply line 22 as a cold heat source used in the liquefier 42. The liquefied combustible gas F supplied to the combustion device 9 is utilized.

The fuel supply line 22 supplies the liquefied combustible gas F from the liquefied combustible gas storage section 21 to the combustion device 9. On the other hand, the fuel supply line 22 of this second embodiment is connected to an exhaust gas cooling tower 130 in order to further use the liquefied combustible gas F used as a cold source in the liquefier 42 of the carbon dioxide liquefaction device 32 as a cold source. leading to. The fuel supply line 22 guides the liquefied combustible gas F used as a cold source in the exhaust gas cooling tower 134 to the vaporizer 23 . In other words, the vaporizer 23 of this second embodiment is provided in the fuel supply line 22 closer to the combustion device 9 than the exhaust gas cooling tower 134 . The vaporizer 23 of this second embodiment is also provided in the middle of the fuel supply line 22 and vaporizes the liquefied combustible gas F, similarly to the first embodiment. Combustible gas G obtained by vaporizing the liquefied combustible gas F is introduced into the combustion device 9 and burned as fuel.

(effect)
According to the second embodiment, similarly to the first embodiment, gaseous carbon dioxide contained in the exhaust gas E discharged from the floating body body 2 is transferred to the absorption tower 35 and the regeneration tower 36 of the carbon dioxide recovery device 31. This allows efficient separation. Therefore, the energy required to separate and liquefy carbon dioxide from the exhaust gas E can be suppressed, and carbon dioxide can be efficiently recovered. Furthermore, since the volume of carbon dioxide can be reduced by liquefying the carbon dioxide separated by the carbon dioxide recovery device 31 in the carbon dioxide liquefaction device 32, the size of the container for storing the recovered carbon dioxide can be avoided. It can be suppressed.

Furthermore, in the second embodiment, the liquefied combustible gas F used as a cold source for the carbon dioxide liquefier 32 is further used as a cold source for the exhaust gas cooling tower 34 and then introduced into the vaporizer 23. As a result, the liquefied combustible gas F, which is the fuel for the combustion device 9, can be heated before being introduced into the vaporizer 23, so that the energy required to vaporize the liquefied combustible gas F in the vaporizer 23 can be It can be further reduced.

《Third embodiment》
Next, a third embodiment of the floating body according to the present disclosure will be described. The third embodiment described below differs in configuration from the second embodiment in that the evaporated gas from which liquefied carbon dioxide has evaporated can be re-liquefied. Therefore, while referring to FIG. 1 and attaching the same reference numerals to the same parts as in the second embodiment, the same parts will be described with reference to FIG. 1, and redundant explanation will be omitted.

FIG. 5 is a diagram showing a schematic configuration of a carbon dioxide recovery system provided in a floating body in a third embodiment of the present disclosure.
As shown in FIGS. 1 and 5, the floating body 1C in the third embodiment, like the floating body 1B in the second embodiment, includes a floating body body 2, a combustion device 9, and a carbon dioxide recovery system 10C (see FIG. 5). , a liquefied carbon dioxide storage section 11 , a liquefied combustible gas storage section 21 , a fuel supply line 22 , and a vaporization device 23 . Furthermore, the floating body 1C of the third embodiment includes a cargo tank 51 provided in the cargo loading section 8, an evaporative gas introduction line 52, a reliquefied carbon dioxide discharge line 53, and valve devices 54, 55, 59, and 57. , is equipped with.

The cargo tank 51 stores liquefied carbon dioxide as cargo. Inside the cargo tank 51, a gas phase exists in the upper part and a liquid phase exists in the lower part. The gas phase mainly consists of evaporated gas (natural BOG) B that is evaporated due to natural heat input into the cargo tank 51.

The evaporative gas introduction line 52 guides the vapor phase gas (evaporative gas B) in the cargo tank 51 to the compressor 41 of the carbon dioxide recovery system 10C. The evaporated gas introduction line 52 of this embodiment is connected to a gaseous carbon dioxide introduction line 37 that guides gaseous carbon dioxide discharged from the carbon dioxide recovery device 31 to the carbon dioxide liquefaction device 32 . That is, the evaporated gas B in the cargo tank 51 can be introduced into the carbon dioxide liquefaction device 32 via the evaporated gas introduction line 52 and the gaseous carbon dioxide introduction line 37. The evaporated gas B in the cargo tank 51 is compressed by the compressor 41 of the carbon dioxide liquefaction device 32, and then cooled by the liquefier 42 using the liquefied combustible gas F as a cold source and re-liquefied.

The reliquefied carbon dioxide discharge line 53 introduces the liquefied carbon dioxide reliquefied by the carbon dioxide liquefaction device 32 into the cargo tank 51. The reliquefied carbon dioxide discharge line 53 of this embodiment is branched and connected to the liquefied carbon dioxide discharge line 43.

The valve devices 54 and 55 are capable of switching the gaseous carbon dioxide introduced into the carbon dioxide liquefaction device 32 into carbon dioxide from the carbon dioxide recovery device 31 and carbon dioxide from the cargo tank 51. There is. Further, the valve devices 56 and 57 are capable of switching the location where the liquefied carbon dioxide liquefied by the carbon dioxide liquefier 32 is stored. That is, the liquefied carbon dioxide liquefied by the carbon dioxide liquefier 32 is stored in either the cargo tank 51 or the liquefied carbon dioxide storage section 11 .

(effect)
According to the third embodiment, in addition to the effects of the first and second embodiments, the evaporated gas B generated in the cargo tank 51 can be reliquefied by the carbon dioxide liquefaction device 32 of the carbon dioxide recovery system 10C. can. Therefore, since there is no need to provide a dedicated reliquefaction device for reliquefying the evaporated gas B, it is possible to suppress the floating body 1 from increasing in size. Also, when re-liquefying the evaporated gas B, the liquefied combustible gas F can be used as a cold source, so further energy savings can be achieved.

Additionally, liquefied carbon dioxide obtained by re-liquefying the evaporated gas B can be returned to the cargo tank 51. Furthermore, liquefied carbon dioxide collected and liquefied by the carbon dioxide recovery device 31 can be stored in the liquefied carbon dioxide storage section 11 . Therefore, if the liquefied carbon dioxide obtained by re-liquefying the evaporated gas B and the liquefied carbon dioxide recovered and liquefied by the carbon dioxide recovery device 31 have different compositions, the liquefied carbon dioxide recovered from the exhaust gas E may be added to the liquefied carbon dioxide as cargo. It is possible to suppress the contamination of liquefied carbon dioxide that has been liquefied.

(Modified example of third embodiment)
In the third embodiment described above, an example has been described in which the carbon dioxide liquefaction device 32 for liquefying carbon dioxide recovered from the exhaust gas E is also used as a reliquefaction device for the evaporated gas B of the cargo tank 51. However, the configuration is not limited to this. For example, only one of the compressor 41 and the liquefier 42 of the carbon dioxide liquefaction device 32 may be used to re-liquefy the evaporated gas B. Also in this case, it is possible to reduce the number of compressors 41 or liquefiers 42 for reliquefaction.

Furthermore, in the third embodiment described above, a case has been described in which the liquefied carbon dioxide discharged from the carbon dioxide liquefaction device 32 is stored separately in the cargo tank 51 and the liquefied carbon dioxide storage section 11, but the liquefied carbon dioxide For example, by providing only one of the storage section 11 and the cargo tank 51, all of the liquefied carbon dioxide discharged from the carbon dioxide liquefaction device 32 is transferred to either the liquefied carbon dioxide storage section 11 or the cargo tank 51. It is also possible to store only the

Furthermore, in the third embodiment described above, a case has been described in which the evaporated gas B generated in the cargo tank 51 is reliquefied by the carbon dioxide liquefaction device 32 of the carbon dioxide recovery system 10C. However, the evaporated gas B is not limited to that generated in the cargo tank 51. For example, as shown by the broken line in FIG. 4, in addition to the evaporative gas B generated in the cargo tank 51, the evaporative gas B generated in the liquefied carbon dioxide storage section 11 is passed through the evaporative gas introduction line 152 to the carbon dioxide liquefier. 32 (the same applies to the fourth embodiment described later). In this case, the evaporative gas B introduced into the carbon dioxide liquefaction device 32 may be selectable from the evaporative gas B of the cargo tank 51 and the evaporative gas B of the liquefied carbon dioxide storage section 11. Alternatively, for example, the cargo tank 51 and the evaporative gas introduction line 52 may be omitted, and the evaporative gas B generated in the liquefied carbon dioxide storage section 11 and the gaseous carbon dioxide discharged from the carbon dioxide recovery device 31 may be replaced with carbon dioxide. It may also be configured so that it can be introduced into the liquefaction device 32.

《Fourth embodiment》
Next, a fourth embodiment of the floating body according to the present disclosure will be described. In the fourth embodiment described below, the evaporated gas B of the cargo tank 51 and the carbon dioxide discharged from the carbon dioxide recovery device 31 are mixed and then introduced into the carbon dioxide liquefaction device 32. The configuration is different. Therefore, while referring to FIG. 1 and attaching the same reference numerals to the same parts as in the second embodiment, the same parts will be described with reference to FIG. 1, and redundant explanation will be omitted.

FIG. 6 is a diagram showing a schematic configuration of a carbon dioxide recovery system provided in a floating body in a fourth embodiment of the present disclosure.
As shown in FIGS. 1 and 6, the floating body 1D in the fourth embodiment, like the floating body 1C in the third embodiment, includes a floating body main body 2, a combustion device 9, and a carbon dioxide recovery system 10D (see FIG. 6). , a liquefied carbon dioxide storage section 11 , a liquefied combustible gas storage section 21 , a fuel supply line 22 , and a vaporization device 23 . The floating body 1D of the fourth embodiment also includes a cargo tank 51 provided in the cargo loading section 8, an evaporative gas introduction line 52, a reliquefied carbon dioxide discharge line 53, valve devices 56 and 57, and an introduction adjustment section. 61.

The introduction adjustment unit 61 adjusts the amount of carbon dioxide introduced from the carbon dioxide recovery device 31 to the carbon dioxide liquefaction device 32 and the amount of carbon dioxide introduced to the carbon dioxide liquefaction device 32 through the evaporative gas introduction line 52. do. The introduction adjustment section 61 includes an inlet detection section 62, an outlet detection section 63, and a control valve 64. The inlet detection unit 62 detects at least the temperature at the inlet of the compressor 41 and outputs the detection result to the control valve 64. The outlet detection unit 63 detects at least the temperature at the outlet of the compressor 41 and outputs the detection result to the control valve 64. The inlet detecting section 62 and the outlet detecting section 63 in this fourth embodiment detect pressure as well as temperature.

The control valve 64 adjusts the opening degree of the flow path in the evaporated gas introduction line 52 based on the detection results of the inlet detection section 62 and the outlet detection section 63. Furthermore, the control valve 64 adjusts the opening degree of the flow path in the gaseous carbon dioxide introduction line 37 based on the detection results of the inlet detection section 62 and the outlet detection section 63. The control valve 64 controls the carbon dioxide introduced from the carbon dioxide recovery device 31 to the carbon dioxide liquefaction device 32 and the evaporated gas introduction line 52 so that the liquefaction of carbon dioxide carried out in the carbon dioxide liquefaction device 32 becomes optimally efficient. It is possible to adjust the mixing ratio at which carbon dioxide is mixed with the carbon dioxide introduced into the carbon dioxide liquefaction device 32. In addition, in this fourth embodiment, although a three-way flow rate adjustment valve is illustrated as the control valve 64, the control valve 64 is not limited to a three-way valve.

Furthermore, the introduction adjustment unit 61 suppresses the discharge temperature at the outlet of the compressor 41 from increasing more than necessary due to the high temperature of the carbon dioxide at the inlet of the compressor 41, and also suppresses the carbon dioxide at the inlet of the compressor 41. This also prevents the filling efficiency of the compressor 41 from decreasing due to an excessive rise in temperature. Further, the introduction adjustment section 61 detects the pressure at the inlet and the pressure at the outlet of the compressor 41 to set the pressure at the outlet of the compressor 41 to a desired pressure and to prevent the compression ratio of the compressor 41 from becoming excessive. In addition, the pressure of carbon dioxide on the inlet side is adjusted.

Here, the carbon dioxide discharged from the regeneration tower 36 and flowing through the gaseous carbon dioxide introduction line 37 is, for example, at room temperature or slightly warmer than room temperature. On the other hand, carbon dioxide discharged from the cargo tank 51 and flowing through the evaporative gas introduction line 52 has a temperature of about -20°C to -30°C, for example. In the introduction adjustment section 61 of this fourth embodiment, the gaseous carbon dioxide discharged from the cargo tank 51 is mixed with the carbon dioxide flowing through the gaseous carbon dioxide introduction line 37, so that the carbon dioxide that is heat exchanged in the liquefier 42 is The temperature difference between the carbon and the liquefied combustible gas F is increased to increase heat exchange efficiency. The above-mentioned mixing ratio at which liquefaction in the liquefier 42 becomes optimally efficient can be determined in advance based on experiments, simulations, and the like. The above-mentioned opening degree adjustment of the control valve 64 is performed, for example, by using a map of the flow rates of the evaporated gas introduction line 52 and the gaseous carbon dioxide introduction line 37 with respect to the detection results of the inlet detection section 62 and the outlet detection section 63 obtained through experiments, simulations, etc. , a table, a mathematical formula, etc.

In this fourth embodiment, a liquefied carbon dioxide storage section 11 and a cargo tank 51 are provided, and it is possible to distribute and store carbon dioxide liquefied by the liquefier 42 in each. An example of how to allocate carbon dioxide to the liquefied carbon dioxide storage section 11 and the cargo tank 51 is to store liquefied carbon dioxide in the one with a larger free capacity. Note that, similarly to the modification of the third embodiment, only one of the liquefied carbon dioxide storage section 11 and the cargo tank 51 is provided, and for example, all of the liquefied carbon dioxide discharged from the carbon dioxide liquefaction device 32 is stored. The liquefied carbon dioxide may be stored only in either the liquefied carbon dioxide storage section 11 or the cargo tank 51. Further, similarly to the modification of the third embodiment, the evaporated gas B of the liquefied carbon dioxide storage section 11 may be introduced into the carbon dioxide liquefier 32.

(effect)
According to the fourth embodiment, in addition to the effects of the first and second embodiments, the evaporated gas B generated in the cargo tank 51 can be re-liquefied by the carbon dioxide liquefaction device 32 of the carbon dioxide recovery system 10D. can. Therefore, since there is no need to provide a dedicated reliquefaction device for reliquefying the evaporated gas B, it is possible to suppress the floating body 1 from increasing in size. Also, when re-liquefying the evaporated gas B, the liquefied combustible gas F can be used as a cold source, so further energy savings can be achieved.

Furthermore, since the evaporated gas B of the cargo tank 51 and the gaseous carbon dioxide discharged from the carbon dioxide recovery device 31 can be mixed and then introduced into the carbon dioxide liquefaction device 32, the discharge temperature at the outlet of the compressor 41 can be adjusted to improve the heat exchange efficiency in the liquefier 42, and the temperature at the inlet of the compressor 41 can be adjusted to improve the filling efficiency of the compressor 41. Therefore, the efficiency of liquefying carbon dioxide can be increased.

《Other embodiments》
The present disclosure is not limited to the configurations of the embodiments described above, and design changes can be made without departing from the gist thereof.
For example, in each of the above embodiments, the floating bodies 1A, 1B, 1C, and 1D are explained using ships as an example, but for example, floating bodies such as FSU (Floating Storage Unit), FSRU (Floating Storage and Regasification Unit), etc. Good too.

Further, in the fourth embodiment described above, a case has been described in which the inlet detection section 62 and the outlet detection section 63 each detect pressure, but the inlet detection section 62 and the outlet detection section 63 are designed to detect only temperature. You can also do this.

<Additional notes>
The floating body described in the embodiment is understood as follows, for example.

(1) According to the first aspect, the floating bodies 1A, 1B, 1C, and 1D include a combustion device 9 that operates using liquefied combustible gas F as fuel and discharges exhaust gas E, and a liquefied combustible gas that stores the liquefied combustible gas F. a combustible gas storage section 21; a fuel supply line 22 that supplies the liquefied combustible gas F from the liquefied combustible gas storage section 21 to the combustion device 9; A carbon dioxide recovery device 31 includes an absorption tower 35 that absorbs the carbon dioxide into carbon dioxide, and a regeneration tower 36 that separates gaseous carbon dioxide from the absorption liquid that has absorbed the carbon dioxide in the absorption tower 35, and the fuel supply line 22. a carbon dioxide liquefaction device 32 that liquefies carbon dioxide discharged from the carbon dioxide recovery device 31 using the liquefied combustible gas F supplied from the liquefied combustible gas storage section 21 to the combustion device 9 as a cold heat source; A liquefied carbon dioxide storage section 11 that stores carbon dioxide liquefied by a carbon dioxide liquefaction device 32 is provided.
Examples of floating bodies include ships such as liquefied gas carriers, ferries, RORO ships, car carriers, passenger ships, FSUs (Floating Storage Units), FSRUs (Floating Storage and Regasification Units), and the like. Examples of the combustion device 9 include an engine (internal combustion engine) for a main engine or a generator, and a boiler. Examples of the liquefied combustible gas F include liquefied natural gas, methane, ethane, and hydrogen.

Thereby, the energy required to separate and liquefy carbon dioxide from the exhaust gas E can be suppressed, and carbon dioxide can be efficiently recovered.

(2) According to the second aspect, the floating body is the floating body of (1), and is connected to the fuel supply line 22 on the side of the combustion device 9 rather than the carbon dioxide liquefaction device 32 in the fuel supply line 22. A vaporizer 23 is provided to vaporize the liquefied combustible gas F used as a cold source in the carbon dioxide liquefaction device 32.
As a result, the energy required to vaporize the liquefied combustible gas F in the vaporizer 23 can be reduced, making it possible to recover carbon dioxide even more efficiently.

(3) According to a third aspect, the floating body is the floating body of (2), and the carbon dioxide recovery device 31 further includes an exhaust gas cooling tower 34 that cools the exhaust gas E discharged from the combustion device 9. The exhaust gas cooling tower 34 cools the exhaust gas E using the liquefied combustible gas F used as a cold source by the carbon dioxide liquefaction device 32 as a cold source, and the vaporizer 23 cools the exhaust gas E using the liquefied combustible gas F used as a cold source by the carbon dioxide liquefaction device 32. The liquefied combustible gas F used as a cold heat source is vaporized.
As a result, the liquefied combustible gas F, which is the fuel for the combustion device 9, can be heated before being introduced into the vaporizer 23, so that the energy required to vaporize the liquefied combustible gas F in the vaporizer 23 can be It can be further reduced.

(4) According to the fourth aspect, the floating body is any one of (1) to (3), and includes a cargo tank 51 that stores liquefied carbon dioxide as a cargo and carbon dioxide generated in the cargo tank 51. The evaporative gas introduction line 52 introduces the evaporated gas B into the carbon dioxide liquefaction device 32, and the evaporative gas introduction line 52 introduces the carbon dioxide introduced from the carbon dioxide recovery device 31 into the carbon dioxide liquefaction device 32. The carbon dioxide liquefier 32 includes a valve device that switches between carbon dioxide and carbon dioxide introduced into the carbon dioxide liquefaction device 32.
This eliminates the need to provide a dedicated reliquefaction device for reliquefying the evaporated gas B, so it is possible to suppress the increase in size of the floating bodies 1C and 1D.

(5) According to the fifth aspect, the floating body is the floating body of (4), in which carbon dioxide is introduced into the carbon dioxide liquefaction device 32 through the evaporative gas introduction line 52 and liquefied in the carbon dioxide liquefaction device 32. A reliquefied carbon dioxide discharge line 53 is provided for returning carbon to the cargo tank 51.
Thereby, for example, liquefied carbon dioxide obtained by reliquefying the evaporated gas B can be returned to the cargo tank 51.

(6) According to the sixth aspect, the floating body is any one of (1) to (3), and includes a cargo tank 51 that stores liquefied carbon dioxide as a cargo and carbon dioxide generated in the cargo tank 51. The carbon dioxide is removed from the carbon dioxide recovery device 31 based on the temperature of the carbon dioxide at least at the inlet of the carbon dioxide liquefaction device 32. The carbon dioxide liquefier 32 includes an introduction adjustment unit 61 that adjusts a mixing ratio for mixing carbon dioxide introduced into the liquefaction device 32 and carbon dioxide introduced into the carbon dioxide liquefaction device 32 through the evaporative gas introduction line 52.
Thereby, the heat exchange efficiency in the carbon dioxide liquefaction device 32 can be increased.

(7) According to the seventh aspect, the floating body is the floating body of (6), and includes a re-liquefied carbon dioxide discharge line 53 that returns the carbon dioxide liquefied in the carbon dioxide liquefaction device 32 to the cargo tank 51. .
This eliminates the need to provide a dedicated reliquefaction device for reliquefying the evaporated gas B, so it is possible to suppress the increase in size of the floating bodies 1C and 1D.

(8) According to the eighth aspect, the carbon dioxide recovery method is a carbon dioxide recovery method for recovering carbon dioxide from exhaust gas E discharged by burning liquefied combustible gas F, the carbon dioxide recovery method comprising: a step S01 in which carbon dioxide is absorbed into an absorption liquid; a step S02 in which gaseous carbon dioxide is separated from the absorption liquid that has absorbed the carbon dioxide; and a step S02 in which gaseous carbon dioxide is separated from the absorption liquid using the liquefied combustible gas F as a cold source. The method includes a step S03 of liquefying the carbon dioxide gas, and a step S04 of storing the liquefied carbon dioxide.

According to the floating body and carbon dioxide recovery method according to the present disclosure, it is possible to efficiently recover carbon dioxide by suppressing the energy required to separate and liquefy carbon dioxide from exhaust gas.

1A, 1B, 1C, 1D... Floating body 2... Floating body main body 2a... Bow 2b... Stern 3A, 3B... Broad side 7... Upper structure 8... Cargo loading compartment 9... Combustion device 10A, 10B, 10C, 10D... Carbon dioxide recovery system 11 ...Liquefied carbon dioxide storage unit 21...Liquefied combustible gas storage unit 22...Fuel supply line 23...Vaporization device 31...Carbon dioxide recovery device 32...Carbon dioxide liquefaction device 34,134...Exhaust gas cooling tower 35...Absorption tower 36...Regeneration tower 37... Gaseous carbon dioxide introduction line 38... Exhaust gas cleaning tower 41... Compressor 42... Liquefier 43... Liquefied carbon dioxide discharge line 51... Cargo tank 52... Evaporated gas introduction line 53... Reliquefied carbon dioxide discharge line 54, 55, 56 , 57...Valve device 61...Introduction adjustment unit 62...Inlet detection unit 63...Outlet detection unit 64...Control valve 152...Evaporative gas introduction line B...Evaporative gas E...Exhaust gas F...Liquefied combustible gas G...Combustible gas

Claims (8)

1. a combustion device that operates using liquefied combustible gas as fuel and discharges exhaust gas;
   a liquefied combustible gas storage section that stores the liquefied combustible gas;
   a fuel supply line that supplies the liquefied combustible gas from the liquefied combustible gas storage section to the combustion device;
   a carbon dioxide recovery device having an absorption tower that causes an absorption liquid to absorb carbon dioxide contained in the exhaust gas; and a regeneration tower that separates gaseous carbon dioxide from the absorption liquid that has absorbed the carbon dioxide in the absorption tower;
   a carbon dioxide liquefaction device that liquefies carbon dioxide discharged from the carbon dioxide recovery device using the liquefied combustible gas supplied from the liquefied combustible gas storage section to the combustion device through the fuel supply line as a cold heat source;
   A floating body comprising: a liquefied carbon dioxide storage section that stores carbon dioxide liquefied by the carbon dioxide liquefaction device.
2. Among the fuel supply lines, a vaporizer is provided in the fuel supply line closer to the combustion device than the carbon dioxide liquefaction device, and vaporizes the liquefied combustible gas used as a cold source in the carbon dioxide liquefaction device. The floating body according to claim 1.
3. The carbon dioxide recovery device further includes an exhaust gas cooling tower that cools the exhaust gas discharged from the combustion device,
   The exhaust gas cooling tower cools the exhaust gas using the liquefied combustible gas used as a cold source by the carbon dioxide liquefaction device as a cold source,
   The floating body according to claim 2, wherein the vaporizer vaporizes the liquefied combustible gas used as a cold source by the exhaust gas cooling tower.
4. A cargo tank that stores liquefied carbon dioxide as cargo;
   an evaporative gas introduction line that introduces evaporative gas generated in the cargo tank to the carbon dioxide liquefaction device;
   From claim 1, comprising a valve device that switches between carbon dioxide introduced from the carbon dioxide recovery device to the carbon dioxide liquefaction device and carbon dioxide introduced into the carbon dioxide liquefaction device through the evaporative gas introduction line. The floating body according to any one of 3.
5. 5. The floating body according to claim 4, further comprising a re-liquefied carbon dioxide discharge line for returning the carbon dioxide introduced into the carbon dioxide liquefaction device by the evaporated gas introduction line and liquefied by the carbon dioxide liquefaction device to the cargo tank.
6. A cargo tank that stores liquefied carbon dioxide as cargo;
   an evaporative gas introduction line that introduces evaporative gas generated in the cargo tank to the carbon dioxide liquefaction device;
   Carbon dioxide is introduced from the carbon dioxide recovery device into the carbon dioxide liquefaction device based on the temperature of the carbon dioxide at least at the inlet of the carbon dioxide liquefaction device, and carbon dioxide is introduced into the carbon dioxide liquefaction device through the evaporated gas introduction line. an introduction adjustment unit that adjusts a mixing ratio to mix the carbon dioxide;
   The floating body according to any one of claims 1 to 3, comprising:
7. The floating body according to claim 6, further comprising a re-liquefied carbon dioxide discharge line that returns the carbon dioxide liquefied by the carbon dioxide liquefaction device to the cargo tank.
8. A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas emitted by burning liquefied combustible gas,
   a step of absorbing carbon dioxide contained in the exhaust gas into an absorption liquid;
   separating gaseous carbon dioxide from the absorption liquid that has absorbed the carbon dioxide;
   liquefying the gaseous carbon dioxide separated from the absorption liquid using the liquefied flammable gas as a cold heat source;
   a step of storing the liquefied carbon dioxide;
   carbon capture methods including;

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