KR20230100809A - Carbon Dioxide Handling System For LCO2 Carrier - Google Patents

Abstract

A carbon dioxide handling system of 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 for storing LNG to be supplied as fuel for an onboard engine; a compressor for receiving and compressing the boil-off gas generated from the carbon dioxide tank; And a heat exchanger that receives the boil-off gas compressed by the compressor and cools it by heat exchange with LNG to be supplied from the fuel tank to the engine; It is characterized by being provided with.

Description

Carbon dioxide handling system of carbon dioxide carrier {Carbon Dioxide Handling System For LCO2 Carrier}

The present invention relates to a carbon dioxide handling system of a carbon dioxide carrier, and more particularly, controls the temperature and pressure of the carbon dioxide tank while storing the carbon dioxide in a liquid state in a carbon dioxide tank provided as a pressure container capable of maintaining the internal pressure above the triple point of carbon dioxide. It relates to a carbon dioxide handling system of a carbon dioxide carrier.

Efforts are being made to reduce greenhouse gas emissions worldwide as the global warming phenomenon intensifies, and as the Kyoto Protocol in 1997, which contained the obligations of developed countries to reduce greenhouse gases, expired in 2020, the conference was held in Paris, France in December 2015. According to the Paris Climate Change Accord, which was adopted in the 21st United Nations Framework Convention on Climate Change and entered into force in November 2016, the 195 Parties participating in the agreement are making various efforts to reduce 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 has increased and various technologies have been developed as pollution-free energy that can replace fossil fuels and nuclear power. are losing

The International Maritime Organization (IMO), a United Nations specialized agency established to internationally unify ship routes, traffic rules, and port facilities, announced that global greenhouse gas emissions from ships will drop from 2.7% in 2007 to 2050. is expected to increase to 12-18% in 2018, and 'prevention of air pollution' was added to Annex VI of the MARPOL Convention to prevent air pollution caused by ships, causing SOx (sulfuric acid), NOx (nitrogen oxide), and ODS (ozone layer destruction) Substances) have been designated as regulated substances.

Accordingly, recently, technologies for using liquefied gases such as LNG, LPG, CNG, and DME as fuel for ships are 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 culprits of air pollution, so it is evaluated as an eco-friendly fuel compared to other fossil fuels. In accordance with the trend of strengthening exhaust gas emission regulations, the number of ships using LNG as a propulsion fuel in addition to LPG or LNG carriers is increasing.

IMO (International Maritime Organization, International Maritime Organization) presents the goal of reducing greenhouse gases by 50% by 2050 and 100% by 2100 (GHG Zero Emission) compared to 2008, and regulations in each country and region accordingly is expected to strengthen.

According to EEDI (Energy Efficiency Design Index), a compulsory carbon dioxide reduction regulation applied by IMO to new ships, in the initial EEDI announcement, CO2 emissions in 2015 were reduced by 10% based on the CO2 emissions from 2013 to 2015 EEDI Phase 1 was applied, and it was scheduled to apply Phase 3 in 2025 by strengthening and applying one step every 5 years. As international interest in climate change and greenhouse gas emissions grows, ships ordered after 2030 decide to reduce carbon emissions by 40% compared to ships ordered in 2008 and by 50% by 2050. Regulations are rapidly strengthening.

In accordance with this trend of strengthening regulations, various technologies are being researched, such as development of eco-friendly fuel technology without carbon dioxide emission, technology for capturing carbon dioxide in fossil fuel combustion gas and converting or liquefying it into methane or methanol. In particular, since the use of fossil fuels is inevitable until the development of economical renewable energy technologies, it is also necessary to develop technologies that can capture and effectively process carbon dioxide generated from the use of fossil fuels.

The present invention intends to propose a method for transporting captured carbon dioxide in a liquid state that is efficient for storage and transport through a ship.

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

A fuel tank for storing LNG to be supplied as fuel for an onboard engine;

a compressor for receiving and compressing the boil-off gas generated from the carbon dioxide tank; and

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

The carbon dioxide handling system of the carbon dioxide carrier is provided, characterized in that the carbon dioxide tank is provided as a pressure container capable of maintaining an internal pressure of at least the triple point of carbon dioxide.

Preferably, the compressor and the heat exchanger are provided, the carbon dioxide cooling line for discharging the boil-off gas of the carbon dioxide tank and recovering it to the carbon dioxide tank via 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 a heater provided in the pressure control line and heating the boil-off gas compressed by the compressor: may further include.

Preferably, when the pressure of the carbon dioxide tank decreases, the boil-off gas generated in 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 at or above the triple point of carbon dioxide to produce dry ice. (dry ice) is prevented from being formed, and when dry ice is formed in the carbon dioxide tank, the boil-off 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 for 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 by the engine, and the LNG in the fuel tank may be transferred to the vaporizer via the heat exchanger.

Preferably, a pressure transmitter for sensing the pressure of the carbon dioxide tank; A first valve provided at the rear end of the branching point of the pressure control line in the carbon dioxide cooling line; and a second valve opening and closing the pressure control line, wherein the first and second valves may be controlled according to the carbon dioxide tank pressure sensed by the pressure transmitter.

Preferably, when the pressure of the carbon dioxide tank sensed by the pressure transmitter is greater than or equal to a first set pressure value, the first valve is opened and the second valve is closed so that the boil-off gas generated in the carbon dioxide tank is passed through the compressor and the heat exchanger. It is supplied to the carbon dioxide tank to lower the internal pressure of the tank, and when the pressure of the carbon dioxide tank sensed by the pressure transmitter is less than or equal to the second set pressure value, the first valve is closed and the second valve is opened to release the boil-off gas generated from the carbon dioxide tank. Carbon dioxide may be supplied to the tank through the compressor and the heater to increase the pressure inside the tank.

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

Preferably, a gas supply line for supplying BOG generated from LNG in the fuel tank as fuel to a gas consumer in 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 heat source supply line for transferring the BOG compressed in the fuel compressor of the gas supply line to a front end of the temperature controller via the heater, wherein the boil-off gas compressed in the compressor includes BOG compressed in the fuel compressor and It may 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 for reducing some of the evaporation gas cooled by heat exchange in the heat exchanger and injecting it into the economizer. The cooled boil-off gas may be additionally cooled through the economizer.

Preferably, a second depressurization device provided downstream of the economizer in the carbon dioxide cooling line reduces the boil-off gas additionally cooled in the economizer and transfers it to the carbon dioxide tank; and a recirculation line for supplying boil-off gas, which has been decompressed by 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 that is more efficient for storage and transportation through ships than solid or gas, while controlling the temperature and pressure of the tank through the treatment of boil-off gas generated in the carbon dioxide tank. .

By using LNG cold heat to be supplied as fuel for the ship's engine, it cools the CO2 boil-off gas, thereby increasing the ship's energy efficiency and reducing operating costs.

1 schematically shows a carbon dioxide handling system of a carbon dioxide carrier according to a first embodiment of the present invention.
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 objects achieved by the practice of 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 configuration and operation of a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are marked with the same numerals as much as possible, even if they are displayed on different drawings.

In embodiments of the present invention described later, a carbon dioxide carrier is provided with a storage tank for storing liquefied carbon dioxide, and liquefied gas such as LNG at a low temperature and boil-off gas generated from liquefied gas are stored in an engine for propulsion or power generation, and inside the ship. It can be any type of vessel that can be used as fuel for engines, etc. In the present embodiments, it will be described as an example that LNG, which is one of representative liquefied gases, is supplied as fuel.

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 according to operating conditions of the system.

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

As shown in FIGS. 1 and 2, the carbon dioxide handling system includes a carbon dioxide tank (CT) provided on the ship and storing liquefied carbon dioxide, and a fuel tank (FT) storing LNG to be supplied as fuel for the inboard engines E1 and E2. ), a compressor 100 that receives and compresses the boil-off gas generated from the carbon dioxide tank, and a heat exchanger 200 that receives the boil-off gas compressed by 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 provided as a pressure container capable of maintaining an internal pressure higher than the triple point of carbon dioxide, and stores carbon dioxide in a liquid state. Since the triple point of carbon dioxide is about 5.18 bara, -56.7°C, dry ice is formed by changing the phase to a solid when cooled under normal atmospheric pressure. In the present embodiments, in order to store and transport carbon dioxide in a liquid state that is more efficient for storage and transport through ships than solids, a carbon dioxide tank (CT) with a pressure container is provided and the pressure inside the tank is increased to increase the carbon dioxide's triple point or higher. The tank temperature and pressure are controlled by processing the evaporation 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 evaporated gas from the carbon dioxide tank and return it to the carbon dioxide tank through the compressor 100 and the heat exchanger 200. The boil-off gas, that is, gaseous carbon dioxide is cooled through a compressor and a heat exchanger and recovered in a liquid state into the tank. That is, the temperature and pressure inside the tank can be lowered by discharging the boil-off gas from the carbon dioxide tank, compressing it, cooling it with cold heat from LNG in the heat exchanger, liquefying it, and then recovering it to the carbon dioxide tank.

In addition, in order to maintain the pressure of the carbon dioxide tank at or above the triple point, a pressure control line (PL) branched from the rear end of the compressor of the carbon dioxide cooling line and connected to the carbon dioxide tank is provided. A heater 300 is provided. In the present embodiments, by configuring the piping so that the compressor 100 of the carbon dioxide cooling line can be used for both purposes instead of a separate compressor for maintaining the tank pressure, the installation cost of the device can be reduced and a compact system can be implemented.

In the carbon dioxide tank (CT), when the tank pressure is higher than a predetermined value due to the generation of evaporation gas, a safety valve (not shown) may be opened and a rapid pressure drop may occur. When such a rapid pressure drop occurs, dry ice may be formed inside the tank by dropping the pressure inside the carbon dioxide tank below the triple point of carbon dioxide.

As such, when the pressure drop occurs in the carbon dioxide tank, in the present embodiments, the carbon dioxide boil-off 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 at or above the triple point of carbon dioxide. Thus, the formation of dry ice in the tank is primarily prevented.

If dry ice is already formed in the carbon dioxide tank before increasing the tank pressure, the evaporated gas in 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 form dry ice in the tank. can melt.

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

If necessary according to the fuel supply pressure of the engine, a pump 450 for pressurizing LNG may be provided at the front end of the heat exchanger of the fuel supply line. The engines E1 and E2 may be a main engine for propulsion and a power generation engine of a ship, and when the fuel supply pressures of the main engine and the power generation engine are different, pressurized LNG according to the fuel supply pressure of the main engine may be supplied to the power generation engine after depressurization. may be

In order to supply cryogenic LNG as engine fuel, a significant amount of thermal energy such as steam is required to heat it to the required temperature in the engine. By heating the recovered LNG to be supplied as engine fuel while lowering the tank temperature and pressure, it is possible to reduce the use of steam, etc., increase the energy efficiency of the ship, and reduce operating costs.

The system according to the second embodiment shown in FIG. 2 has some components added to the system according to the first embodiment to increase energy efficiency and smoothly control the temperature and pressure of the carbon dioxide tank. Description of the overlapping configuration will be omitted and the added configuration will be described.

As shown in FIG. 2, in the second embodiment, a pressure transmitter (PT) for detecting the pressure of the carbon dioxide tank is provided so that each device for controlling the temperature and pressure of the tank can be operated according to the internal pressure of the carbon dioxide tank, 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), a first valve (V1) for opening and closing the pipe is provided, and a second valve (V2) is provided 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 increasing device can be automatically switched according to the pressure of the carbon dioxide tank detected by the pressure transmitter (PT).

First, when the pressure of the carbon dioxide tank detected by the pressure transmitter (PT) is equal to or greater than the first set pressure value, the first valve (V1) is opened and the second valve (V2) is closed to release the boil-off gas generated in the carbon dioxide tank (CT) to the compressor ( 100) and the heat exchanger 200 to supply carbon dioxide to the tank to lower the pressure inside the tank.

When the pressure of the carbon dioxide tank detected by the pressure transmitter (PT) is less than the second set pressure value, the first valve (V1) is closed and the second valve (V2) is opened to transfer the evaporated gas generated from the carbon dioxide tank to the compressor 100 and the heater ( 300) to supply the carbon dioxide tank (CT) to increase the pressure inside the tank.

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

On the other hand, as a heat source of the heater 300, BOG (Boil-Off Gas) generated from LNG in the fuel tank FT can be supplied as fuel for a gas consumer on board and utilized as a heat source of the heater. A gas supply line (GL) for supplying BOG from a fuel tank to a gas consumer on board is connected, and a fuel compressor (500) for compressing BOG according to the fuel supply pressure of a gas consumer is connected to the gas supply line, and BOG compressed in the fuel compressor A temperature controller 550 is provided to adjust the temperature according to the fuel supply temperature of the gas consumer.

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

The gas consumption source may be, for example, engines E1 and E2 such as an onboard power generation engine or a main engine. The temperature of the BOG compressed in the fuel compressor 500 increases according to the fuel supply pressure to the gas consumer, and when the temperature of the fuel supply 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 boil-off gas, thereby reducing the amount of cooling heat required in the temperature controller and securing a heat source for heating the carbon dioxide boil-off gas to increase energy efficiency.

On the other hand, in the present embodiment, the first economizer 250 is provided downstream of the heat exchanger 200 in the carbon dioxide cooling line CL, reduces some of the boil-off gas cooled by heat exchange in the heat exchanger, and injects it into the economizer. A pressure reducing device (EV1) is provided. The evaporation gas, which has been 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 first pressure reducing device (EV1). The remaining boil-off gas not diverted to the pressure reducer can be additionally cooled in the economizer.

A second decompression device (EV2) is provided downstream of the economizer 250 in the carbon dioxide cooling line (CL) to reduce the boil-off gas additionally cooled by the economizer and transfer it to the carbon dioxide tank (CT). The carbon dioxide in the carbon dioxide cooling line additionally cooled in the economizer is expanded and cooled through the second pressure reducing device and returned to the carbon dioxide tank, thereby further lowering the internal temperature of the tank. The boil-off gas depressurized by the first pressure reducing device and injected into the economizer cools the carbon dioxide in the carbon dioxide cooling line, and then is supplied to the front end of the compressor of the carbon dioxide cooling line along the recirculation line (RL) to be recycled.

It is obvious to those skilled in the art that the present invention is not limited to the above embodiments and can be variously modified or modified without departing from the technical gist of the present invention. it did

CT: Carbon Dioxide Tank
FT: fuel tank
E1, E2: engine
CL: CO2 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 for storing LNG to be supplied as fuel for an onboard engine;
a compressor for receiving and compressing the boil-off gas generated from the carbon dioxide tank; and
A heat exchanger that receives the boil-off gas compressed by the compressor and cools it by heat exchange with LNG to be supplied from the fuel tank to the engine,
The carbon dioxide handling system of the carbon dioxide carrier, characterized in that the carbon dioxide tank is provided as a pressure container capable of maintaining the internal pressure at a triple point or higher of carbon dioxide. According to claim 1,
a carbon dioxide cooling line provided with the compressor and heat exchanger and discharging boil-off gas from the carbon dioxide tank and returning it to the carbon dioxide tank via 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; and
The carbon dioxide handling system of the carbon dioxide carrier further comprising a heater provided in the pressure control line and heating the boil-off gas compressed by the compressor. According to claim 2,
When the pressure of the carbon dioxide tank decreases, the boil-off gas generated in 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 at or above the triple point of carbon dioxide to produce dry ice. prevent the formation of
When dry ice is formed in the carbon dioxide tank, the evaporated 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 claim 2,
a fuel supply line supplying LNG from the fuel tank to the engine; and
Further comprising a vaporizer provided in the fuel supply line and heating the LNG to a temperature required by the engine,
The carbon dioxide handling system of the carbon dioxide carrier, characterized in that the LNG in the fuel tank is transferred to the vaporizer through the heat exchanger. According to claim 4,
a pressure transmitter for sensing the pressure of the carbon dioxide tank;
A first valve provided at the rear end of the branching point of the pressure control line in the carbon dioxide cooling line; and
A second valve for opening and closing the pressure control line further includes,
The carbon dioxide handling system of the carbon dioxide carrier, characterized in that the first and second valves are controlled according to the pressure of the carbon dioxide tank detected by the pressure transmitter. According to claim 5,
When the pressure of the carbon dioxide tank sensed by the pressure transmitter is equal to or higher than the first set pressure value, the first valve is opened and the second valve is closed to supply the evaporated gas generated in the carbon dioxide tank to the carbon dioxide tank through the compressor and the heat exchanger. to lower the pressure inside the tank,
When the pressure of the carbon dioxide tank sensed by the pressure transmitter is equal to or less than the second set pressure value, the first valve is closed and the second valve is opened to supply evaporated gas generated in the carbon dioxide tank to the carbon dioxide tank through the compressor and the heater. Carbon dioxide handling system of a carbon dioxide carrier, characterized in that to increase the pressure inside the tank. According to claim 6,
The first and second set pressure values are carbon dioxide handling systems of a carbon dioxide carrier, characterized in that a constant value between the carbon dioxide triple point and the design pressure of the carbon dioxide tank. According to claim 5,
a gas supply line supplying BOG generated from the LNG in the fuel tank as fuel to a gas consumer onboard;
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 for transferring the BOG compressed in the fuel compressor of the gas supply line to a front end of the thermostat via the heater;
The carbon dioxide handling system of the 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 claim 8,
an economizer provided downstream of the heat exchanger in the carbon dioxide cooling line; and
A first pressure reducing device for reducing some of the evaporation gas cooled by heat exchange in the heat exchanger and injecting it into the economizer;
The carbon dioxide handling system of the carbon dioxide carrier, characterized in that the boil-off gas cooled by heat exchange in the heat exchanger by the boil-off gas reduced by the first pressure reducing device is additionally cooled through the economizer. According to claim 9,
a second decompression device provided downstream of the economizer in the carbon dioxide cooling line to depressurize the boil-off gas additionally cooled in the economizer and transfer it to the carbon dioxide tank; and
The carbon dioxide handling system of the carbon dioxide carrier further comprising: a recirculation line for supplying boil-off gas decompressed by 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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