KR102647305B1 - Carbon Dioxide Handling System For LCO2 Carrier - Google Patents

Abstract

A carbon dioxide handling system for a carbon dioxide carrier is disclosed. The carbon dioxide handling system of the carbon dioxide carrier of the present invention includes a carbon dioxide tank provided on the ship and storing liquefied carbon dioxide; A fuel tank that stores LNG to be supplied as fuel for the ship's engines; A compressor that receives and compresses the evaporation gas generated from the carbon dioxide tank; and a heat exchanger that receives compressed boil-off gas from the compressor and cools it by heat exchange with LNG to be supplied from the fuel tank to the engine, wherein the carbon dioxide tank is a pressure vessel capable of maintaining an internal pressure above the triple point of carbon dioxide. It is characterized by being provided as.

Description

Carbon Dioxide Handling System For LCO2 Carrier}

The present invention relates to a carbon dioxide handling system for a carbon dioxide carrier, and more specifically, to controlling the temperature and pressure of the carbon dioxide tank while storing carbon dioxide in a liquid state in a carbon dioxide tank provided as a pressure vessel capable of maintaining the internal pressure above the triple point of carbon dioxide. This is about the carbon dioxide handling system of a carbon dioxide carrier.

As the global warming phenomenon intensifies, efforts are being made to reduce greenhouse gas emissions around the world, and as the 1997 Kyoto Protocol, which included obligations for developed countries to reduce greenhouse gases, expires in 2020, the event held in Paris, France in December 2015 The 195 parties participating in the Paris Climate Change Accord, which was adopted at the 21st United Nations Framework Convention on Climate Change and came into effect in November 2016, are making various efforts with the goal of 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 UN specialized organization established to internationally unify shipping routes, traffic rules, port facilities, etc., predicted that global greenhouse gas emissions from ships will decrease from 2.7% in 2007 to 2050. It is expected to increase to 12-18%, and to prevent air pollution caused by ships, 'Air pollution prevention' was added to Annex VI of the MARPOL agreement to prevent SOx (sulfuric acid substances), NOx (nitrogen oxides), and ODS (ozone depletion-causing substances). substances) 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.

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.

The present invention seeks to propose a method for transporting captured carbon dioxide through ships in a liquid state that is efficient for storage and transportation.

According to one aspect of the present invention for solving the above-described problem, a carbon dioxide tank provided on a ship and storing liquefied carbon dioxide;

A fuel tank that stores LNG to be supplied as fuel for the ship's engines;

A compressor that receives and compresses the evaporation gas generated from the carbon dioxide tank; and

A heat exchanger that receives compressed boil-off gas from the compressor and cools it by heat exchange with LNG to be supplied from the fuel tank to the engine,

A carbon dioxide handling system for a carbon dioxide carrier is provided, wherein the carbon dioxide tank is provided as a pressure vessel capable of maintaining an internal pressure above the triple point of carbon dioxide.

Preferably, the compressor and the heat exchanger are provided, and the carbon dioxide cooling line discharges the evaporation gas of the carbon dioxide tank and returns it to the carbon dioxide tank through the compressor and the heat exchanger; A pressure control line branched from the rear end of the compressor of the carbon dioxide cooling line and connected to the carbon dioxide tank; And it may further include a heater provided in the pressure control line and heating the boil-off gas compressed in the compressor.

Preferably, when the pressure of the carbon dioxide tank decreases, the evaporation gas generated from the carbon dioxide tank is compressed by the compressor and supplied to the carbon dioxide tank through the pressure control line to maintain the pressure inside the tank above the triple point of carbon dioxide to produce dry ice. (dry ice) is prevented from forming, and when dry ice is formed in the carbon dioxide tank, the evaporation gas from the carbon dioxide tank is discharged, pressurized and heated through the compressor and heater, and then supplied to the carbon dioxide tank to melt the dry ice. there is.

Preferably, a fuel supply line supplying LNG from the fuel tank to the engine; and a vaporizer provided in the fuel supply line to heat the LNG to a temperature required for the engine, wherein the LNG in the fuel tank may be transferred to the vaporizer through the heat exchanger.

Preferably, a pressure transmitter that senses the pressure of the carbon dioxide tank; a first valve provided at a rear end of a branch point of the pressure control line in the carbon dioxide cooling line; and a second valve that opens and closes the pressure control line, wherein the first and second valves can be controlled according to the pressure of the carbon dioxide tank detected by the pressure transmitter.

Preferably, when the pressure of the carbon dioxide tank detected by the pressure transmitter is greater than the first set pressure value, the first valve is opened and the second valve is closed to allow the evaporation gas generated in the carbon dioxide tank to pass through the compressor and the heat exchanger to the The pressure inside the tank is lowered by supplying it to the carbon dioxide tank, and when the pressure of the carbon dioxide tank detected by the pressure transmitter is below the second set pressure value, the first valve is closed and the second valve is opened to remove the evaporation gas generated from the carbon dioxide tank. Carbon dioxide can be supplied to the tank through the compressor and heater to increase the pressure inside the tank.

Preferably, the first and second set pressure values may be a constant value between the carbon dioxide triple point and the design pressure of the carbon dioxide tank.

Preferably, a gas supply line that supplies BOG generated from the LNG in the fuel tank as fuel to the gas consumer on board; a fuel compressor provided in the gas supply line to compress the BOG according to the fuel supply pressure of the gas consumer; a temperature controller that adjusts the BOG compressed in the fuel compressor to the fuel supply temperature of the gas consumer; And a heat source supply line that transfers the BOG compressed in the fuel compressor of the gas supply line to the front of the temperature controller via the heater, wherein the boil-off gas compressed in the compressor is combined with the BOG compressed in the fuel compressor. It can be heated by heat exchange in the heater.

Preferably, an economizer provided downstream of the heat exchanger in the carbon dioxide cooling line; And a first decompression device that depressurizes some of the boil-off gas cooled by heat exchange in the heat exchanger and injects it into the economizer, wherein the boil-off gas depressurized in the first decompression device causes heat exchange in the heat exchanger. The cooled evaporation gas may be further cooled through the economizer.

Preferably, a second decompression device is provided downstream of the economizer in the carbon dioxide cooling line to depressurize the boil-off gas further cooled in the economizer and transfer it to the carbon dioxide tank; and a recirculation line that supplies the boil-off gas decompressed in the first pressure reducing device and injected into the economizer to a front end of the compressor of the carbon dioxide cooling line.

In the present invention, carbon dioxide can be stored and transported in a liquid state, which is more efficient for storage and transportation by ship than solid or gas, and the tank temperature and pressure can be controlled through the treatment of boil-off gas generated in the carbon dioxide tank. .

It improves the ship's energy efficiency and reduces operating costs by cooling carbon dioxide evaporation gas using the LNG cold heat that will be supplied as fuel for the ship's engine.

Figure 1 schematically shows a carbon dioxide handling system of a carbon dioxide carrier according to a first embodiment of the present invention.
Figure 2 schematically shows a carbon dioxide handling system of a carbon dioxide carrier according to a second 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 carbon dioxide carrier is provided with a storage tank for storing liquefied carbon dioxide, and liquefied gas liquefied at low temperature, such as LNG, and boil-off gas generated from the liquefied gas are used in engines for propulsion or power generation, inside the ship. It can be any type of ship that can be used as fuel for engines, etc. In the present embodiments, LNG, one of the representative liquefied gases, is supplied as fuel as an example.

Meanwhile, the fluid flowing through each line of the present embodiments may be in any one of a liquid state, a gas-liquid mixture state, a gas state, and a supercritical fluid state, depending on the operating conditions of the system.

Figure 1 schematically shows a carbon dioxide handling system of a carbon dioxide carrier according to a first embodiment of the present invention, and Figure 2 schematically shows a carbon dioxide handling system of a second embodiment.

As shown in Figures 1 and 2, the carbon dioxide handling system is provided on the ship and includes a carbon dioxide tank (CT) that stores liquefied carbon dioxide, and a fuel tank (FT) that stores LNG to be supplied as fuel for the onboard engines (E1 and E2). ), a compressor (100) that receives and compresses the boil-off gas generated from a carbon dioxide tank, and a heat exchanger (200) that receives the compressed boil-off gas from the compressor and cools it by heat exchange with LNG to be supplied to the engine from the fuel tank. .

The carbon dioxide tank is a pressure vessel that can maintain the internal pressure above the triple point of carbon dioxide and stores carbon dioxide in a liquid state. The triple point of carbon dioxide is about 5.18 bara, -56.7°C, so when cooled under atmospheric pressure, it changes phase into a solid to form dry ice. In the present embodiments, a carbon dioxide tank (CT) made of a pressure vessel is provided to store and transport carbon dioxide in a liquid state, which is more efficient for storage and transportation by ship than solid, and the pressure inside the tank is increased to exceed the triple point of carbon dioxide. The tank temperature and pressure are controlled by treating the boil-off gas generated from the carbon dioxide tank to maintain the pressure and maintain the tank temperature at a low temperature below the boiling point of carbon dioxide at the corresponding pressure. For example, the carbon dioxide tank (CT) may be provided as an independent Type C tank, and the fuel tank (FT) may be provided as a Type B or Type C tank or a membrane type tank.

First, in order to cool the carbon dioxide tank, a carbon dioxide cooling line (CL) is provided to discharge the evaporation gas of the carbon dioxide tank and return it to the carbon dioxide tank through the compressor 100 and the heat exchanger 200, thereby removing the carbon dioxide generated from the liquefied carbon dioxide in the carbon dioxide tank. Boil-off gas, or gaseous carbon dioxide, is cooled through a compressor and heat exchanger and returned to the tank in liquid form. In other words, the temperature and pressure inside the tank can be lowered by discharging and compressing the boil-off gas from the carbon dioxide tank, cooling it with LNG cold heat in a heat exchanger, liquefying it, and then returning it to the carbon dioxide tank.

In addition, in order to maintain the pressure of the carbon dioxide tank above the triple point, a pressure control line (PL) is provided that branches off from the rear end of the compressor of the carbon dioxide cooling line and connects to the carbon dioxide tank, and the pressure control line contains a pressure control line that heats the boil-off gas compressed in the compressor. A heater 300 is provided. In these embodiments, the piping is configured so that the compressor 100 of the carbon dioxide cooling line can be used concurrently instead of a separate compressor for maintaining tank pressure, thereby reducing device installation costs and implementing a compact system.

In a carbon dioxide tank (CT), when the tank pressure rises above a certain value due to the generation of evaporative gas, a safety valve (not shown) may open and a rapid pressure drop may occur. If this rapid pressure drop occurs, the pressure inside the carbon dioxide tank may drop below the carbon dioxide triple point and dry ice may form inside the tank.

In this way, when a pressure drop occurs in the carbon dioxide tank, in the present embodiments, the carbon dioxide evaporation gas is compressed in the compressor 100 and then supplied to the carbon dioxide tank through the pressure control line (PL) to maintain the pressure inside the tank above the triple point of carbon dioxide. This primarily prevents the formation of dry ice in the tank.

If dry ice has already been formed in the carbon dioxide tank before increasing the tank pressure, the evaporation gas from the carbon dioxide tank is discharged, pressurized and heated through the compressor 100 and heater 300, and then supplied to the carbon dioxide tank to dry ice formed in the tank. can be melted.

A fuel supply line (LL) is provided to supply LNG from the fuel tank (FT) to the engine (E1), and a vaporizer (400) is provided in the fuel supply line to heat the LNG to the temperature required by the engine. The LNG in the fuel tank is transferred by the fuel supply pump (FP) in the tank, passes through the heat exchanger 200, exchanges heat with the carbon dioxide boil-off gas, and cools the carbon dioxide boil-off gas. The LNG is preheated and transferred to the vaporizer 400. In the carburetor, the preheated LNG is further heated to the temperature required by the engine through a heat exchanger and supplied to the engine.

If necessary depending on the fuel supply pressure of the engine, a pump 450 that pressurizes LNG may be provided at the front of the heat exchanger of the fuel supply line. The engines (E1, E2) may be the ship's main propulsion engine and power generation engine, and when the fuel supply pressure of the main engine and the power generation engine are different, LNG pressurized according to the fuel supply pressure of the main engine can be decompressed and then supplied to the power generation engine. It may be possible.

In order to supply extremely low temperature LNG as engine fuel, a significant amount of heat energy such as steam is required to heat the engine to the required temperature. In the present embodiments, the carbon dioxide boil-off gas is cooled through heat exchange with the carbon dioxide boil-off gas and transferred to the carbon dioxide tank. By recovering and lowering the tank temperature and pressure while simultaneously heating the LNG to be supplied as engine fuel, the use of steam, etc. can be reduced, the ship's energy efficiency can be increased, and operating costs can be reduced.

The second embodiment system shown in FIG. 2 adds some components to the first embodiment system to further increase energy efficiency and smoothly control the temperature and pressure of the carbon dioxide tank. The description of the duplicated configuration will be omitted and the added configuration will be explained.

As shown in FIG. 2, in the second embodiment, a pressure transmitter (PT) is provided to detect the pressure of the carbon dioxide tank so that each device for controlling the tank temperature and pressure can be operated according to the internal pressure of the carbon dioxide tank, There is a first valve (V1) that opens and closes the pipe at the rear end of the branch point of the pressure control line (PL) downstream of the compressor (100) in the carbon dioxide cooling line (CL), and a second valve (V2) in the pressure control line (PL). Each is provided. The first and second valves are controlled so that the operation of the cooling device and the pressure raising device can be automatically switched according to the carbon dioxide tank pressure detected by the pressure transmitter (PT).

First, if the carbon dioxide tank pressure detected by the pressure transmitter (PT) is higher than the first set pressure value, the first valve (V1) is opened and the second valve (V2) is closed to allow the evaporation gas generated from the carbon dioxide tank (CT) to be sent to the compressor ( 100) and heat exchanger 200 to supply carbon dioxide to the tank to lower the pressure inside the tank.

If the carbon dioxide tank pressure detected by the pressure transmitter (PT) is below the second set pressure value, close the first valve (V1) and open the second valve (V2) to allow the evaporation gas generated from the carbon dioxide tank to be sent to the compressor (100) and the heater ( 300), the pressure inside the tank can be increased by supplying it to the carbon dioxide tank (CT).

The first setting pressure value is when the operation of the cooling process equipment is required, and when the carbon dioxide tank pressure is equal to or higher than the pressure corresponding to the first setting pressure value, the boil-off gas is cooled, reliquefied, and sent to the tank to lower the tank temperature and pressure. do. The second setting pressure value is a case where the operation of a pressure increasing device is required. When the carbon dioxide tank pressure is equal to or lower than the pressure corresponding to the second setting pressure value, the boil-off gas is compressed and heated and sent to the tank to increase the pressure inside the tank. The dry ice formed in can be melted. The first and second setting pressure values are constant values between the carbon dioxide triple point and the design pressure of the carbon dioxide tank. For example, the first setting pressure value is 9 barg. The second setting pressure value may be set to 6 barg.

Meanwhile, as a heat source for the heater 300, BOG (Boil-Off Gas) generated from LNG in the fuel tank (FT) can be supplied as fuel to gas consumers on board and used as a heat source for the heater. A gas supply line (GL) that supplies BOG from the fuel tank to the gas consumer on board is connected, and the gas supply line includes a fuel compressor 500 that compresses the BOG according to the fuel supply pressure of the gas consumer, and the BOG compressed in the fuel compressor. A temperature controller 550 is provided to adjust the fuel supply temperature of the gas consumer.

A heat source supply line (HL) is provided that transfers the BOG compressed from the fuel compressor of the gas supply line through a heater to the front of the temperature controller, and the boil-off gas compressed in the compressor 100 is connected to the BOG compressed in the fuel compressor 500. It can be heated by heat exchange in the heater 300.

The gas consumer may be, for example, an engine (E1, E2) such as the ship's power generation engine or the main engine. The temperature of the BOG compressed in the fuel compressor 500 increases depending on the fuel supply pressure to the gas consumer, and if the fuel supply temperature to the gas consumer is lower than the temperature of the compressed BOG, it must be cooled through the temperature controller 550. In this embodiment, the high-temperature BOG is sent to the heater to heat the carbon dioxide evaporation gas, thereby reducing the amount of cooling heat required in the temperature controller and securing a heat source for heating the carbon dioxide evaporation gas to increase energy efficiency.

Meanwhile, in this embodiment, the economizer 250 is provided downstream of the heat exchanger 200 in the carbon dioxide cooling line (CL), and the first economizer 250 depressurizes some of the boil-off gas cooled by heat exchange in the heat exchanger and sprays it into the economizer. A pressure reducing device (EV1) is provided. The evaporative gas expanded and cooled by the Joule-Thomson effect through decompression in the first pressure reducing device (EV1) is injected into the economizer 250, cooled by heat exchange in the heat exchanger 200, and then cooled by heat exchange in the heat exchanger 200. The remaining evaporation gas that has not been diverted to the pressure reducing device can be additionally cooled in the economizer.

Downstream of the economizer 250 in the carbon dioxide cooling line (CL), a second decompression device (EV2) is provided to depressurize the boil-off gas further cooled in the economizer and transfer it to the carbon dioxide tank (CT). The carbon dioxide in the carbon dioxide cooling line that has been additionally cooled in the economizer is expanded and cooled through a second pressure reduction device and returned to the carbon dioxide tank, thereby further lowering the temperature inside the tank. The evaporation gas decompressed in the first pressure reducing device and injected into the economizer cools the carbon dioxide in the carbon dioxide cooling line and is then supplied to the front of the compressor of the carbon dioxide cooling line along the recirculation line (RL) and recirculated.

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.

CT: carbon dioxide tank
FT: Fuel tank
E1, E2: Engine
CL: Carbon dioxide cooling line
PL: Pressure control line
100: Compressor
200: heat exchanger
300: Heater

Claims (10)

A carbon dioxide tank provided on the ship and storing liquefied carbon dioxide;
A fuel tank that stores LNG to be supplied as fuel for the ship's engines;
A compressor that receives and compresses the evaporation gas generated from the carbon dioxide tank;
A heat exchanger that receives compressed boil-off gas from the compressor and cools it by heat exchange with LNG to be supplied from the fuel tank to the engine;
a carbon dioxide cooling line provided with the compressor and a heat exchanger, discharging evaporation gas from the carbon dioxide tank and returning it to the carbon dioxide tank through the compressor and heat exchanger;
A pressure control line branched from the rear end of the compressor of the carbon dioxide cooling line and connected to the carbon dioxide tank;
a heater provided in the pressure control line and heating the boil-off gas compressed in the compressor;
A gas supply line that supplies BOG generated from the LNG in the fuel tank as fuel to gas consumers on board the ship;
a fuel compressor provided in the gas supply line to compress the BOG according to the fuel supply pressure of the gas consumer;
a temperature controller that adjusts the BOG compressed in the fuel compressor to the fuel supply temperature of the gas consumer; and
A carbon dioxide handling system for a carbon dioxide carrier comprising: a heat source supply line that transfers the BOG compressed in the fuel compressor of the gas supply line to the front of the temperature controller via the heater. According to clause 1,
A carbon dioxide handling system for a carbon dioxide carrier, characterized in that the carbon dioxide tank is provided as a pressure vessel capable of maintaining an internal pressure above the triple point of carbon dioxide. According to clause 2,
When the pressure of the carbon dioxide tank decreases, the evaporation gas generated from the carbon dioxide tank is compressed by the compressor and supplied to the carbon dioxide tank through the pressure control line to maintain the pressure inside the tank above the triple point of carbon dioxide to create dry ice. prevent the formation,
When dry ice is formed in the carbon dioxide tank, the evaporation gas from the carbon dioxide tank is discharged, pressurized and heated through the compressor and heater, and then supplied to the carbon dioxide tank to melt the dry ice. . According to clause 2,
A fuel supply line that supplies LNG from the fuel tank to the engine; and
It further includes: a vaporizer provided in the fuel supply line to heat the LNG to the temperature required by the engine,
A carbon dioxide handling system for a carbon dioxide carrier, characterized in that the LNG in the fuel tank is transferred to the vaporizer through the heat exchanger. According to clause 4,
A pressure transmitter that senses the pressure of the carbon dioxide tank;
a first valve provided at a rear end of a branch point of the pressure control line in the carbon dioxide cooling line; and
It further includes a second valve that opens and closes the pressure control line,
A carbon dioxide handling system for a carbon dioxide carrier, characterized in that the first and second valves are controlled according to the carbon dioxide tank pressure detected by the pressure transmitter. According to clause 5,
If the pressure of the carbon dioxide tank detected by the pressure transmitter is greater than the first set pressure value, the first valve is opened and the second valve is closed to supply the boil-off gas generated in the carbon dioxide tank to the carbon dioxide tank through the compressor and heat exchanger. This lowers the pressure inside the tank,
If the pressure of the carbon dioxide tank detected by the pressure transmitter is less than the second set pressure value, the first valve is closed and the second valve is opened to supply the evaporation gas generated in the carbon dioxide tank to the carbon dioxide tank through the compressor and heater. A carbon dioxide handling system for a carbon dioxide carrier characterized by increasing the pressure inside the tank. According to clause 6,
The first and second set pressure values are a constant value between the carbon dioxide triple point and the design pressure of the carbon dioxide tank. According to clause 5,
A carbon dioxide handling system for a carbon dioxide carrier, characterized in that the boil-off gas compressed in the compressor is heated by heat exchange with the BOG compressed in the fuel compressor in the heater. According to clause 8,
An economizer provided downstream of the heat exchanger in the carbon dioxide cooling line; and
It further includes a first decompression device that depressurizes some of the evaporation gas cooled by heat exchange in the heat exchanger and sprays it into the economizer,
A carbon dioxide handling system for a carbon dioxide carrier, characterized in that the boil-off gas cooled by heat exchange in the heat exchanger by the boil-off gas decompressed in the first pressure reducing device is further cooled through the economizer. According to clause 9,
A second decompression device provided downstream of the economizer in the carbon dioxide cooling line to depressurize the boil-off gas further cooled in the economizer and transfer it to the carbon dioxide tank; and
A carbon dioxide handling system for a carbon dioxide carrier further comprising: a recirculation line that supplies the boil-off gas decompressed in the first pressure reducing device and injected into the economizer to a front end of the compressor of the carbon dioxide cooling line.

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