KR20240044591A - Carbon Dioxide Capture System For Ship - Google Patents

Abstract

The ship's carbon dioxide capture system is launched. The ship's carbon dioxide capture system of the present invention includes a carbon dioxide collection line that separates carbon dioxide from flue gas generated from a combustion device that uses LNG as fuel on a ship, cools it, and liquefies it; An LNG storage tank provided on the ship and storing LNG; A fuel compressor that receives and compresses the boil-off gas generated from the LNG in the LNG storage tank; A re-liquefaction line that re-liquefies the compressed gas compressed in the fuel compressor and returns it to the LNG storage tank; And a reliquefaction heat exchanger provided in the reliquefaction line and in which the compressed gas is cooled by the cold heat of uncompressed boil-off gas to be supplied to the fuel compressor, wherein the carbon dioxide in the carbon dioxide collection line is cooled through the reliquefaction heat exchanger. It is characterized by

Description

Carbon Dioxide Capture System For Ship}

The present invention relates to a carbon dioxide capture system for ships, and more specifically, to separate and liquefy carbon dioxide from flue gas generated from the combustion device of ships using LNG as fuel, and to use the heat energy of the flue gas in a reboiler. It relates to a ship's carbon dioxide capture system that supplies the cooled flue gas through a reboiler to a cooling tower to reduce the amount of seawater or fresh water required to cool the flue gas, and cools the separated carbon dioxide with the cold heat of LNG boil-off gas.

As the global warming phenomenon intensifies, efforts are being made around the world to reduce greenhouse gas emissions.

As the 1997 Kyoto Protocol, which included obligations for developed countries to reduce greenhouse gases, expires in 2020, the Paris Climate Change Agreement (Paris Climate Change) was adopted at the 21st United Nations Framework Convention on Climate Change held in Paris, France in December 2015 and came into effect in November 2016. The 195 parties that participated in the agreement (Change Accord) are making various efforts aimed at reducing greenhouse gases.

Along with this global trend, interest in renewable energy (or renewable energy) such as wind power, solar power, solar heat, bioenergy, tidal power, and geothermal heat as a pollution-free energy that can replace fossil fuels and nuclear power is increasing, and various technologies are being developed. I'm losing.

The International Maritime Organization (IMO), a United Nations specialized organization established to internationally unify shipping routes, traffic rules, port facilities, etc., predicted that global greenhouse gas emissions from ships will increase from 2.7% in 2007 to 2050. It is expected to increase to 12-18%, and in order to prevent air pollution caused by ships, 'Air pollution prevention' has been added to Annex VI of the MARPOL agreement to reduce SOx (sulfuric acid substances), NOx (nitrogen oxides), and ODS (ozone depletion substances). ), etc. have been designated as regulated substances.

Accordingly, the technology of using liquefied gases such as LNG, LPG, CNG, and DME as ship fuel has recently been in the spotlight. In particular, LNG emits more than 20% less carbon dioxide than coal-based fuels such as bunker C oil, and furthermore, it emits almost no nitrogen oxides and sulfur oxides, which are the main causes of air pollution, so it is evaluated as an eco-friendly fuel compared to other fossil fuels and is recognized internationally. In accordance with the trend of strengthening exhaust gas emission regulations, the number of ships using LNG as propulsion fuel in addition to LPG or LNG carriers is increasing.

Although LNG is considered an eco-friendly fuel compared to other fossil fuels, it still produces carbon dioxide when burned, and ships that use it as fuel emit carbon dioxide during operation.

IMO (International Maritime Organization) sets a goal of reducing greenhouse gases by 50% in 2050 and 100% in 2100 (GHG Zero Emission) compared to 2008, and regulates each country and region accordingly. is expected to be strengthened.

According to EEDI (Energy Efficiency Design Index), a mandatory carbon dioxide reduction regulation applied by IMO to new ships, the initial EEDI announcement called for a 10% reduction in carbon dioxide emissions in 2015 based on carbon dioxide emissions from 2013 to 2015. EEDI Phase 1 was applied, and it was planned to apply Phase 3 in 2025 by strengthening and applying one step every five years. However, for LPG carriers, EEDI Phase 3 will be applied early from 2022, two years after applying EEDI Phase 2. As international interest in climate change and greenhouse gas emissions grows, it has been decided that ships ordered after 2030 will reduce carbon emissions by 40% compared to ships ordered in 2008, and by 50% by 2050. Regulations are rapidly being strengthened.

In accordance with this trend of strengthening regulations, various technologies are being researched, such as the development of eco-friendly fuel technology without carbon dioxide emissions and technology to capture carbon dioxide in fossil fuel combustion gas and convert it into methane or methanol or liquefy it. In particular, since the use of fossil fuels is inevitable until economical new and renewable energy technologies are developed, there is a need to develop technologies that can capture and effectively treat carbon dioxide generated from the use of fossil fuels.

According to one aspect of the present invention for solving the above-described problem, a carbon dioxide collection line that separates carbon dioxide from flue gas generated from a combustion device using LNG as fuel on a ship, cools it, and liquefies it;

An LNG storage tank provided on the ship and storing LNG;

A fuel compressor that receives and compresses the boil-off gas generated from the LNG in the LNG storage tank;

A re-liquefaction line that re-liquefies the compressed gas compressed in the fuel compressor and returns it to the LNG storage tank; and

A reliquefaction heat exchanger provided in the reliquefaction line and in which the compressed gas is cooled by the cold heat of uncompressed boil-off gas to be supplied to the fuel compressor,

A carbon dioxide capture system for ships is provided, wherein the carbon dioxide in the carbon dioxide collection line is cooled through the reliquefaction heat exchanger.

Preferably, a cooling tower provided in the carbon dioxide collection line and cooling the flue gas; An absorption tower that separates and collects carbon dioxide from the flue gas cooled in the cooling tower; A regeneration tower that receives a solution containing carbon dioxide from the absorption tower and separates carbon dioxide; And a carbon dioxide compressor that receives and compresses the carbon dioxide separated from the regeneration tower, wherein the carbon dioxide compressed in the carbon dioxide compressor can be cooled in the reliquefaction heat exchanger.

Preferably, a reboiler that receives the solution from the regeneration tower, heats it, and re-supplies it to the regeneration tower; A branch line that branches off from the carbon dioxide capture line, bypasses the reboiler, and joins the carbon dioxide capture line at the front of the cooling tower; And a branch valve provided in the branch line, wherein the reboiler heats the solution by receiving heat energy from the flue gas at the cooling tower upstream of the carbon dioxide collection line, and all or part of the flue gas is It may be cooled in the reboiler and supplied to the cooling tower.

Preferably, a first temperature sensor detecting the temperature of flue gas at a rear end of the confluence of the branch line in the carbon dioxide collection line; and a first temperature control unit that controls the bypass valve according to the flue gas temperature detected by the first temperature sensor.

Preferably, a post-cooler for cooling the carbon dioxide compressed in the carbon dioxide compressor; A bypass line that branches off from the post-cooler downstream of the carbon dioxide collection line, bypasses the reliquefaction heat exchanger, and joins the carbon dioxide collection line; and a bypass valve provided in the bypass line.

Preferably, a second temperature sensor detecting the carbon dioxide temperature downstream of the bypass valve of the bypass line; a second temperature control unit that outputs a signal for controlling the bypass valve according to the carbon dioxide temperature detected by the second temperature sensor; A pressure sensor that detects carbon dioxide pressure downstream of the bypass valve of the bypass line; a pressure control unit that outputs a signal for controlling the bypass valve according to the carbon dioxide pressure detected by the pressure sensor; and a multi-controller that receives signals output from the second temperature control unit and the pressure control unit to control the bypass valve.

Preferably, a boosting compressor provided in front of the reliquefaction heat exchanger of the reliquefaction line to further compress the compressed gas to be compressed in the fuel compressor and introduced into the reliquefaction heat exchanger; A refrigerant replenishment line that branches off a portion of the compressed gas downstream of the fuel compressor and supplies it to an uncompressed boil-off gas flow to be introduced into the reliquefaction heat exchanger; A compander compressor provided in the refrigerant replenishment line, receives compressed gas from the fuel compressor, further compresses it, and introduces it into the reliquefaction heat exchanger; And a compander expander provided in the refrigerant replenishment line and receiving compressed gas cooled through a reliquefaction heat exchanger after additional compression in the compander compressor to expand and cool the compressed gas, wherein the compander compressor is connected to the compander expander. When connected, the compressed gas can be further compressed by the expansion energy of the compressed gas.

Preferably, a decompression device provided in the reliquefaction line to receive the compressed gas cooled in the reliquefaction heat exchanger and depressurize and cool it; And a gas-liquid separator that receives the compressed gas cooled in the pressure reducing device and separates gas-liquid, wherein the liquid separated from the gas-liquid separator is supplied to the LNG storage tank, and the separated gas is introduced into the reliquefaction heat exchanger. It may join the uncompressed boil-off gas.

Preferably, the combustion device includes an engine for propulsion of the ship, and the fuel compressor compresses the boil-off gas to the fuel supply pressure of the engine and supplies it as fuel, and surplus compressed gas remaining after supplying fuel to the engine. Can be reliquefied through the reliquefaction line.

Preferably, the flue gas is cooled by seawater or fresh water in the cooling tower, and the flue gas in which carbon dioxide is separated and collected in the absorption tower can be discharged overboard.

In the present invention, carbon dioxide is captured, separated, and liquefied from flue gas generated from a ship's combustion device, but the heat energy of the flue gas is used in a reboiler and the cooled flue gas is supplied to the cooling tower through the reboiler, thereby producing refrigerant gas. It is possible to secure the heat source needed for the boiler and reduce the amount of seawater or fresh water needed to cool the flue gas.

In addition, the carbon dioxide to be separated from the flue gas and liquefied is cooled using the cold heat of the boil-off gas generated in the LNG storage tank, thereby increasing the ship's energy efficiency and reducing operating costs.

Through this, carbon dioxide emitted from ships can be minimized and greenhouse gas emissions can be reduced to create eco-friendly ships.

Figure 1 schematically shows a conventional carbon dioxide capture system.
Figure 2 schematically shows a carbon dioxide capture system on a ship according to an embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objectives achieved by practicing the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the structure and operation of a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Here, in adding reference numerals to components in each drawing, it should be noted that identical components are indicated with the same reference numerals as much as possible, even if they are shown in different drawings.

In the embodiments of the present invention described later, the ship may be any type of ship equipped with a storage tank for storing liquefied gas. Representative examples include ships with self-propelled capabilities such as LNG carriers, liquid hydrogen carriers, LNG RVs (Regasification Vessels), carbon dioxide carriers (CO ₂ Carriers), and LNG Fueled Ships (LFS), as well as LNG FPSOs (Floating Production Ships). Offshore structures that do not have propulsion capabilities but are floating in the sea, such as Storage Offloading (Storage Offloading) and LNG FSRU (Floating Storage Regasification Unit), may also be included.

In addition, this embodiment can be applied to all types of liquefied gas that can be transported by liquefying gas at low temperature, generate boil-off gas in a stored state, and be supplied as fuel for combustion devices such as onboard engines. These liquefied gases are, for example, liquefied petrochemicals such as LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), Liquefied Ethylene Gas, and Liquefied Propylene Gas. It could be gas. However, in the examples described later, the application of LNG, a representative liquefied gas, will be described as an example.

Figure 1 schematically shows a conventional carbon dioxide capture system, and Figure 2 schematically shows an improved carbon dioxide capture system for a ship according to an embodiment of the present invention.

First, looking at the carbon dioxide capture system shown in Figure 1, the engine, fuel cell, Aux. Flue gas containing carbon dioxide generated from combustion devices such as boilers is supplied to the carbon dioxide collection line (CL) and transferred to the cooling tower (quenching tower, 20) through the blowing fan (10). In the cooling tower, high temperature flue gas of over 200℃ is cooled to around 40℃ using seawater or fresh water, and soot, particles, and sulfur components contained in the flue gas are removed and supplied to the absorption tower (absorber, 30). .

In the absorption tower, carbon dioxide is captured and separated from flue gas using an absorbent and supplied to the regeneration tower (stripper, 40). An amine-based absorbent may be used as the absorbent, and the absorbent in which carbon dioxide is dissolved in the regeneration tower is heated by steam through a reboiler (50), and the carbon dioxide and absorbent are separated and circulated to the regeneration tower. The absorbent is transferred to the absorption tower, and the carbon dioxide is liquefied from the regeneration tower through a compressor 60 and a liquefaction unit 70 including a cooler, and then transferred to a tank and stored.

These systems require a large amount of seawater or fresh water to cool high-temperature flue gas in the cooling tower, and the reboiler also uses a large amount of steam as a heat source for carbon dioxide separation, so the energy consumption required for system operation is high. The system according to an embodiment of the present invention, which will be described later, is designed to improve this problem and effectively capture carbon dioxide while increasing the energy efficiency of ships.

As shown in Figure 2, the ship's carbon dioxide capture system of this embodiment is a carbon dioxide capture line (CL) that separates carbon dioxide from flue gas generated from the ship's combustion device using LNG as fuel and liquefies it. , a cooling tower 120 that is provided in the carbon dioxide collection line and cools the flue gas, an absorption tower 130 that separates and collects carbon dioxide from the flue gas cooled in the cooling tower, and receives a solution containing carbon dioxide from the absorption tower to separate carbon dioxide. It includes a regeneration tower 140 that receives the solution from the regeneration tower, heats it, and re-supplies it to the regeneration tower.

In this embodiment, the reboiler 150 receives thermal energy from flue gas upstream of the cooling tower of the carbon dioxide collection line to heat the solution, and all or part of the flue gas is cooled in the reboiler and supplied to the cooling tower 120. .

The ship is equipped with an LNG storage tank (T) that stores LNG to be supplied as fuel to the combustion device. As described above, the combustion device (E) is an engine such as a ship's propulsion engine or power generation engine, a fuel cell, and an Aux. It may be a boiler, etc. LNG stored in an LNG storage tank and boil-off gas (Boil Off Gas) generated from LNG can be supplied as fuel to these combustion devices. For this purpose, a fuel supply line (not shown) that supplies LNG is connected to a gas supply line (GL) that supplies boil-off gas to the combustion device. A fuel compressor 200 is provided in the gas supply line to compress boil-off gas according to the fuel supply pressure of a combustion device such as a propulsion engine, and the boil-off gas compressed in the fuel compressor is supplied as fuel for a propulsion engine, etc.

When carbon-based fuel such as LNG is burned in a combustion device, high-temperature flue gas is generated, and the flue gas contains a large amount of carbon dioxide.

The flue gas generated from the combustion device is supplied to the cooling tower 120 along the carbon dioxide collection line (CL) through the blower fan 110 and cooled. In this embodiment, all or part of the high-temperature flue gas before flowing into the cooling tower is sent to the reboiler. It is supplied to (150) and after heat recovery, it is supplied to the cooling tower. Through this, the amount of seawater or fresh water required for cooling flue gas can be reduced in the cooling tower, and in the reboiler, the heat energy of flue gas is used to separate carbon dioxide and amine-based absorbent, significantly reducing the amount of steam required for the reboiler and improving the energy efficiency of the ship. It can be raised.

For this purpose, the carbon dioxide collection line (CL) is connected to the cooling tower 120 through the reboiler 150, and in order to control the temperature of the reboiler, it branches off from the carbon dioxide collection line (CL) and bypasses the reboiler 150 to the cooling tower. (120) A branch line (BL) joining the carbon dioxide collection line is provided at the front end, and a branch valve (BV) is provided in the branch line. In the carbon dioxide collection line, a first temperature sensor (TT1) is provided at the rear end of the junction of the branch lines to detect the flue gas temperature, and a first temperature sensor (TT1) to control the bypass valve according to the flue gas temperature detected by the first temperature sensor. A temperature control unit (TC1) is provided. According to the flue gas temperature detected by the first temperature sensor, the first temperature control unit (TC1) controls the branch valve (BV) to pass the flue gas that bypasses the reboiler (150) through the branch line (BL) and the reboiler. By controlling the flue gas flow rate, the reboiler can be adjusted to the appropriate temperature required for separation of carbon dioxide and amine-based absorbent. In addition, if the entire amount of flue gas flows into the cooling tower through the reboiler, changes in the flue gas discharge rate may cause problems such as increased back pressure in the combustion device, especially the turbocharger of the engine, and increased fuel consumption. This problem can be solved by allowing some of the flue gas to be discharged to the cooling tower without passing through the reboiler.

In the cooling tower 120, the flue gas partially cooled through the reboiler is cooled to around 40°C using seawater or fresh water, and soot, particles, and sulfur components contained in the flue gas are removed, and then transferred to an absorption tower (absorber). 130).

In the absorption tower, carbon dioxide is captured and separated from flue gas using a solvent such as an amine-based absorbent and supplied to the regeneration tower (stripper, 140). Flue gas from which carbon dioxide has been removed in the absorption tower can be discharged overboard.

The solution in which carbon dioxide is collected is supplied to the regeneration tower 140, then passed through the reboiler 150 and heated by flue gas thermal energy to separate carbon dioxide and the absorbent. The absorbent is supplied to the absorption tower 130 and reused, and the carbon dioxide is Carbon dioxide is supplied from the regeneration tower 140 to the carbon dioxide compressor 160 along the carbon dioxide collection line (CL). The carbon dioxide compressed in the carbon dioxide compressor is liquefied through a cooling process and transferred to the carbon dioxide storage tank. For this purpose, a post-cooler 170 that cools the carbon dioxide compressed in the carbon dioxide compressor is provided in the carbon dioxide collection line (CL). Furthermore, in this embodiment system, the reliquefaction heat exchanger provided in the ship's LNG boil-off gas reliquefaction system was configured to be utilized for carbon dioxide cooling.

The LNG boil-off gas re-liquefaction system is a system that can re-liquefy the boil-off gas generated from LNG stored in an LNG storage tank and return it to the LNG storage tank. As shown in Figure 2, it branches off from the gas supply line downstream of the fuel compressor. A re-liquefaction line (RL) connected to the LNG storage tank is provided, and compressed gas is cooled in the re-liquefaction line by heat exchange with uncompressed boil-off gas to be supplied from the LNG storage tank to the fuel compressor 200 along the gas supply line. A reliquefaction heat exchanger (220) is provided.

A boosting compressor 210 is provided in front of the reliquefaction heat exchanger of the reliquefaction line, and can further compress the compressed gas to be compressed in the fuel compressor and cooled in the reliquefaction heat exchanger. In the case of methane, the main component of LNG, the critical point is about -80℃ and 55bar. When re-liquefying boil-off gas generated from LNG, the higher the compression pressure of the boil-off gas, the higher the re-liquefaction rate. The amount of re-liquefaction is highest when compressed around 150 to 170 bar, but there is a significant change in the amount of re-liquefaction between 150 and 300 bar. does not exist. Therefore, in order to effectively re-liquefy the boil-off gas, it is desirable to compress it to 100 bar or more, preferably 150 bar to 300 bar, but the propulsion engine supplied with boil-off gas as fuel does not require such high-pressure fuel. In this case, the fuel compressor 200 compresses only up to the fuel supply pressure of the propulsion engine, further compresses the compressed gas to be reliquefied in the boosting compressor 210, and then cools it in the reliquefaction heat exchanger 220, thereby installing and operating a large-capacity high-pressure compressor. The reliquefaction rate can be increased while reducing the costs.

In addition, this reliquefaction system is equipped with a refrigerant replenishment line (ML) that branches off a portion of the compressed gas downstream of the fuel compressor and supplies it to the uncompressed boil-off gas flow to be introduced into the reliquefaction heat exchanger, and the refrigerant replenishment line (ML) provides fuel. A compander compressor (250A) receives the compressed gas from the compressor, further compresses it, and introduces it into the reliquefaction heat exchanger, and after additional compression from the compander compressor, cooled compressed gas is supplied through the reliquefaction heat exchanger (220) to expand and cool. A compander expander (250B) may be additionally provided. The compander compressor is connected to the compander expander by a shaft so that it can be driven by receiving the expansion energy of the compressed gas. In this way, part of the boil-off gas compressed in the fuel compressor is branched to the refrigerant replenishment line, goes through additional compression, cooling, and expansion cooling, and is then supplied to the re-liquefaction heat exchanger to supplement the uncompressed boil-off gas flow at the front, forming the refrigerant (cold BOG) of the re-liquefaction heat exchanger. By increasing the flow rate, the boil-off gas to be re-liquefied can be cooled more effectively and the re-liquefaction rate can be increased.

The reliquefaction line (RL) is provided with a decompression device 230 that receives compressed gas cooled from the reliquefaction heat exchanger, decompresses it, and cools it, and a gas-liquid separator 240 that receives compressed gas cooled from the decompression device and separates gas and liquid. . The pressure reducing device 230 may be an expansion valve such as an expander or Joule-Thompson valve that adiabatically expands and cools the compressed and cooled boil-off gas, and compresses and cools the compressed and cooled evaporation gas through a fuel compressor, boosting compressor, reliquefaction heat exchanger, and pressure reducing device. All or part of the boil-off gas is re-liquefied and introduced into the gas-liquid separator 240.

The liquid separated in the gas-liquid separator is supplied and stored in the LNG storage tank (T) along the reliquefaction line (RL), and the separated gas is merged into the gas supply line (GL) to combine with the uncompressed boil-off gas generated from the LNG storage tank. Together, it can be supplied as a refrigerant to the reliquefaction heat exchanger (220).

As discussed above, the boil-off gas generated in the LNG storage tank is compressed in a fuel compressor and supplied as fuel for propulsion engines, etc., and the excess compressed gas remaining after fuel supply is re-liquefied through a re-liquefaction system and returned to the LNG storage tank. , In this embodiment, the reliquefaction heat exchanger 220 of the reliquefaction system is used for cooling and liquefying carbon dioxide.

To this end, the carbon dioxide capture line (CL) is cooled through the reliquefaction heat exchanger 220 downstream of the post-cooler 170, as shown in FIG. 2.

At this time, the triple point of carbon dioxide is about 5.18 bara, -56.7°C, and when carbon dioxide heat exchanges with a large amount of cryogenic LNG boil-off gas in a reliquefaction heat exchanger, it can phase change to a solid and form dry ice. To prevent this, a bypass line (BL2) that branches off from the post-cooler downstream of the carbon dioxide collection line, bypasses the reliquefaction heat exchanger and joins the carbon dioxide collection line, and a bypass valve (BV) provided in the bypass line were constructed.

A second temperature sensor (TT2) that detects the carbon dioxide temperature and a pressure sensor (PT) that detects the carbon dioxide pressure are provided downstream of the bypass valve in the bypass line. A second temperature control unit (TC2) that outputs a signal for controlling the bypass valve according to the carbon dioxide temperature detected by the second temperature sensor, and outputs a signal for controlling the bypass valve according to the carbon dioxide pressure detected by the pressure sensor. A pressure control unit (PC2) is provided, and signals output from the second temperature control unit and the pressure control unit are received by the multi-controller (UC) to control the bypass valve (BV2).

While the second temperature sensor and pressure sensor detect the temperature and pressure of carbon dioxide, the signal output from the second temperature control unit and the pressure control unit controls the bypass valve in the multi-controller to prevent carbon dioxide from falling below the triple point. By controlling the flow rate of carbon dioxide passing through the liquefaction heat exchanger and the carbon dioxide passing through the bypass line, dry ice can be prevented and carbon dioxide can be stored in liquid form, which is more efficient for storage and transportation by ship than solid.

In this way, by using the on-board re-liquefaction system through the system of this embodiment, the cold heat necessary for carbon dioxide liquefaction can be secured, carbon dioxide can be captured, and installation costs due to installation of additional devices can be reduced.

It is obvious to those skilled in the art that the present invention is not limited to the above-mentioned embodiments, and that it can be implemented with various modifications or variations without departing from the technical gist of the present invention. It was done.

T: LNG storage tank
CL: Carbon dioxide capture line
110: blowing fan
120: Cooling tower
130: Absorption tower
140: Regeneration tower
150: Reboiler
160: compressor
170: Post-cooler
200: Fuel compressor
210: Boosting compressor
220: Reliquefaction heat exchanger

Claims (10)

A carbon dioxide collection line that separates carbon dioxide from flue gas generated from combustion devices that use LNG as fuel on ships, cools it, and liquefies it;
An LNG storage tank provided on the ship and storing LNG;
A fuel compressor that receives and compresses the boil-off gas generated from the LNG in the LNG storage tank;
A re-liquefaction line that re-liquefies the compressed gas compressed in the fuel compressor and returns it to the LNG storage tank; and
A reliquefaction heat exchanger provided in the reliquefaction line and in which the compressed gas is cooled by the cold heat of uncompressed boil-off gas to be supplied to the fuel compressor,
A ship's carbon dioxide capture system, characterized in that the carbon dioxide in the carbon dioxide collection line is cooled through the reliquefaction heat exchanger. According to clause 1,
A cooling tower provided in the carbon dioxide capture line and cooling the flue gas;
An absorption tower that separates and collects carbon dioxide from the flue gas cooled in the cooling tower;
A regeneration tower that receives a solution containing carbon dioxide from the absorption tower and separates carbon dioxide; and
It further includes a carbon dioxide compressor that receives and compresses the carbon dioxide separated from the regeneration tower,
A ship's carbon dioxide capture system, characterized in that the carbon dioxide compressed in the carbon dioxide compressor is cooled in the reliquefaction heat exchanger. According to clause 2,
A reboiler that receives the solution from the regeneration tower, heats it, and resupplies it to the regeneration tower;
A branch line that branches off from the carbon dioxide capture line, bypasses the reboiler, and joins the carbon dioxide capture line at the front of the cooling tower; and
It further includes a branch valve provided in the branch line,
The reboiler heats the solution by receiving thermal energy from the flue gas upstream of the cooling tower of the carbon dioxide collection line, and all or part of the flue gas is cooled in the reboiler and supplied to the cooling tower. Ship's carbon dioxide capture system. According to clause 3,
A first temperature sensor that detects the temperature of flue gas behind the confluence of the branch line in the carbon dioxide capture line; and
A carbon dioxide capture system for a ship further comprising: a first temperature control unit that controls the bypass valve according to the flue gas temperature detected by the first temperature sensor. According to clause 3,
A post-cooler that cools the carbon dioxide compressed in the carbon dioxide compressor;
A bypass line that branches off from the post-cooler downstream of the carbon dioxide collection line, bypasses the reliquefaction heat exchanger, and joins the carbon dioxide collection line; and
A ship's carbon dioxide capture system further comprising: a bypass valve provided in the bypass line. According to clause 5,
a second temperature sensor that detects carbon dioxide temperature downstream of the bypass valve of the bypass line;
a second temperature control unit that outputs a signal for controlling the bypass valve according to the carbon dioxide temperature detected by the second temperature sensor;
A pressure sensor that detects carbon dioxide pressure downstream of the bypass valve of the bypass line;
a pressure control unit that outputs a signal for controlling the bypass valve according to the carbon dioxide pressure detected by the pressure sensor; and
A ship's carbon dioxide capture system further comprising: a multi-controller that receives signals output from the second temperature control unit and the pressure control unit to control the bypass valve. According to any one of claims 1 to 6,
A boosting compressor provided in front of the reliquefaction heat exchanger of the reliquefaction line to further compress the compressed gas to be compressed in the fuel compressor and introduced into the reliquefaction heat exchanger;
A refrigerant replenishment line that branches off a portion of the compressed gas downstream of the fuel compressor and supplies it to an uncompressed boil-off gas flow to be introduced into the reliquefaction heat exchanger;
A compander compressor provided in the refrigerant replenishment line, receives compressed gas from the fuel compressor, further compresses it, and introduces it into the reliquefaction heat exchanger; and
It is provided in the refrigerant replenishment line and further includes a compander expander that receives compressed gas cooled through a reliquefaction heat exchanger after additional compression in the compander compressor and expands and cools the compressed gas,
The compander compressor is connected to the compander expander and further compresses the compressed gas by the expansion energy of the compressed gas. According to clause 7,
A decompression device provided in the reliquefaction line to receive the compressed gas cooled in the reliquefaction heat exchanger and depressurize it to cool it; and
It includes a gas-liquid separator that receives the compressed gas cooled from the pressure reducing device and separates gas-liquid,
The liquid separated in the gas-liquid separator is supplied to the LNG storage tank, and the separated gas is joined to the uncompressed boil-off gas introduced into the reliquefaction heat exchanger. According to clause 8,
The combustion device includes a propulsion engine of the ship,
The fuel compressor compresses the evaporation gas to the fuel supply pressure of the engine and supplies it as fuel,
A ship's carbon dioxide capture system, characterized in that surplus compressed gas remaining after supplying fuel to the engine is re-liquefied through the re-liquefaction line. According to clause 9,
In the cooling tower, the flue gas is cooled by seawater or fresh water,
A ship's carbon dioxide capture system, characterized in that the flue gas from which carbon dioxide is separated and collected in the absorption tower is discharged overboard.

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